If you’re searching for a foot spa with heat, you’re looking for a way to soothe tired feet and promote relaxation at home. The UNIFULL Collapsible Foot Spa stands out as the overall best choice, offering easy storage and reliable heating. For those seeking added features, the Ranjova Collapsible Foot Spa provides bubble and shiatsu massage balls, while the Medical King Foot Spa excels with powerful jets for deeper relief. The main tradeoffs involve balancing features like massage types and ease of use against price and maintenance requirements. Keep reading to see how each option compares and find the perfect fit for your needs.
Get health and wellness essentials delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
Complete the kit
Key Takeaways
- Top picks combine effective heating with versatile massage features for comprehensive foot care.
- Collapsible designs offer convenient storage and portability, but may compromise on durability for some users.
- Additional features like bubbles, jets, and remote controls significantly enhance relaxation but often come at a higher price.
- Ease of use and cleaning are critical factors that can impact daily enjoyment and maintenance.
- Price varies widely, with premium models offering more features, while budget options focus on essential heat and massage functions.
| UNIFULL Collapsible Foot Spa Bath with Heat and Remote Control |  | Best Overall for Versatile Home Use | Material: 50% Rubber, 40% Plastic, 10% Metal | Heat System: PTC heating | Features: Shiatsu rollers, bubble jets, collapsible design, water drain | VIEW ON AMAZON | See Our Full Breakdown |
| Ranjova Collapsible Foot Spa with Heat, Bubble, and Shiatsu Massage Balls |  | Best for Customizable, Personal Comfort | Massage Balls: 24 motorized Shiatsu balls | Temperature Range: 95°F to 118°F | Timer: 10 to 60 minutes | VIEW ON AMAZON | See Our Full Breakdown |
| OOAMBB Collapsible Foot Spa with Heat, Bubble, and Temp Control |  | Best for Simple, User-Friendly Use | Temperature Range: 95°F to 118°F | Timer: Not specified | Features: Bubble jets, simple controls | VIEW ON AMAZON | See Our Full Breakdown |
| CARESKYpro Collapsible Foot Spa with Fast Heat UL-Listed Foot Soaking Tub |  | Best for Targeted Foot Care with Deep Massage | Target Use: Foot | Power Source: Corded Electric | Features: Bubble jets, wide manual rollers, remote control | VIEW ON AMAZON | See Our Full Breakdown |
| Large Collapsible Foot Spa Bath Massage with Heat, Electric Foot Soaking Tub |  | Best for Larger Feet and Customizable Features | Foot Space: Extra large, fits up to men’s size 14+ | Water Temperature Range: 95°F to 118°F | Timer: 10–60 minutes | VIEW ON AMAZON | See Our Full Breakdown |
| HOSPAN Collapsible Foot Spa with Heat, Bubble & Massage |  | Best for Customizable Relaxation and Space-Saving Design | Temperature Range: 95°F-118°F | Timer: 10 to 60 minutes | Massage Rollers: 8 groups | VIEW ON AMAZON | See Our Full Breakdown |
| Medical King Foot Spa with Heat, Massage, and Jets |  | Best for Multi-Function Massage and Travel-Friendly Use | Heating: Adjustable with temperature control | Bubbles: Oxygen bubbles for circulation | Vibration: Yes | VIEW ON AMAZON | See Our Full Breakdown |
| KNQZE Collapsible Foot Spa Bath with Heat & Remote Control, Bubble Massage, Temperature Control, Red Light (Black) |  | Best for Remote Convenience and Safety Features | Timer: 20 or 60 minutes | Control: Remote control | Color: Black | VIEW ON AMAZON | See Our Full Breakdown |
| Collapsible Electric Foot Spa with Heat, Bubble, and Remote Control |  | Best for Compact Storage with Advanced Massage Features | Massage Balls: 6 groups of 3D Tai Chi massage balls | Temperature Range: 95°F to 118°F | Control: Remote control included | VIEW ON AMAZON | See Our Full Breakdown |
| OOAMBB Collapsible Foot Spa Bath with Remote Control, Heat, Bubble, Timer |  | Best for Versatile Features and Travel-Ready Design | Water Temperature Range: 95°F to 118°F | Timer Options: 10, 20, 30, 40, 50, 60 minutes | Folded Height: 4.74 inches | VIEW ON AMAZON | See Our Full Breakdown |
| foot spa with heat | Timer | Features | Temperature Range |
|---|---|---|---|
| UNIFULL Collapsible Foot Spa B | — | Shiatsu rollers, bubble jets, collapsible design, water drain | — |
| Ranjova Collapsible Foot Spa w | 10 to 60 minutes | — | 95°F to 118°F |
| OOAMBB Collapsible Foot Spa wi | Not specified | Bubble jets, simple controls | 95°F to 118°F |
| CARESKYpro Collapsible Foot Sp | — | Bubble jets, wide manual rollers, remote control | — |
| Large Collapsible Foot Spa Bat | 10–60 minutes | — | — |
| HOSPAN Collapsible Foot Spa wi | 10 to 60 minutes | — | 95°F-118°F |
| Medical King Foot Spa with Hea | — | — | 3 levels |
| KNQZE Collapsible Foot Spa Bat | 20 or 60 minutes | Heat, Bubble Massage, Red Light | — |
| Collapsible Electric Foot Spa | 10 to 60 minutes | — | 95°F to 118°F |
| OOAMBB Collapsible Foot Spa Ba | — | Heat, Bubble Jets, Red Light, Massage Rollers, Pumice Stone, Remote Control | — |
More Details on Our Top Picks
UNIFULL Collapsible Foot Spa Bath with Heat and Remote Control
This model stands out for combining multiple features like Shiatsu rollers, bubble jets, and a collapsible design, making it a comprehensive foot care solution. Compared to the smaller, less feature-rich options like the OOAMBB, the UNIFULL offers a more versatile experience, though it’s slightly bulkier when set up. Its durable construction supports up to 18,000 uses, providing long-term value for dedicated foot enthusiasts. The remote control adds convenience, but some users find the remote functions limited or unclear. While not as portable as smaller models, its space-saving foldability helps balance storage needs with functionality.
Pros:- Includes Shiatsu rollers and bubble jets for effective massage
- Collapsible design for easy storage and portability
- Comes with a pedicure kit and material box for added convenience
- Durable construction supporting up to 18,000 uses
Cons:- Some users may find the size limited for larger feet
- Requires electricity for heating and massage functions
Best for: Home users seeking a multi-featured, durable foot spa with easy storage.
Not ideal for: Travelers or those with limited storage space who need a more compact unit.
- Material:50% Rubber, 40% Plastic, 10% Metal
- Heat System:PTC heating
- Features:Shiatsu rollers, bubble jets, collapsible design, water drain
- Durability:Up to 18,000 uses
Our verdict“This pick is best for those who want a versatile, long-lasting foot spa for regular use at home.”
Ranjova Collapsible Foot Spa with Heat, Bubble, and Shiatsu Massage Balls
This model excels for those who want adjustable heat and massage modes, thanks to its 24 motorized Shiatsu massage balls and touch screen controls. Compared to the UNIFULL, it offers more personalized massage options, although it may take some time to master all functions. The foldable design makes it easy to store, but the massage balls may not provide deep tissue relief for everyone. It’s ideal for users who prioritize customizable comfort but don’t need extensive extra features like pedicure tools or additional accessories.
Pros:- Adjustable heat and massage modes for personalized comfort
- Removable components for easy cleaning and hygiene
- Foldable design for compact storage
- Touch screen control for easy operation
Cons:- May take time to fully assemble and understand controls
- Limited to home use, not suitable for travel
- Massage balls may not deliver deep tissue relief for all users
Best for: Individuals seeking personalized foot relaxation with easy-to-adjust settings.
Not ideal for: People requiring intense deep-tissue massage or those who prefer plug-and-play simplicity without much setup.
- Massage Balls:24 motorized Shiatsu balls
- Temperature Range:95°F to 118°F
- Timer:10 to 60 minutes
- Foldable Height:5.5 inches
- Control:Touch screen
- Additional Features:Bubble jets, auto temperature maintenance, removable massage base and balls
Our verdict“Ideal for users who want tailored foot massages and adjustable heat in a space-saving design.”
OOAMBB Collapsible Foot Spa with Heat, Bubble, and Temp Control
This pick makes the most sense for users who want straightforward controls and basic features, including temperature adjustment and bubble jets. Compared with the more feature-rich UNIFULL and Ranjova, the OOAMBB offers a simpler, motorless massage experience, which may limit deep tissue benefits but simplifies operation. Its collapsible design enhances portability, yet it lacks the advanced massage options of other models. This unit is ideal for casual users who prioritize ease of use over extensive features or customization, though it might fall short for those seeking more therapeutic massage options.
Pros:- Simple control panel with temperature and bubble settings
- Collapsible for easy storage and portability
- Affordable price point for basic foot soaking needs
Cons:- Limited massage features without motorized discs
- Less suitable for users seeking deep tissue or targeted massage
Best for: Casual users or seniors who prefer simple, easy-to-operate foot spas.
Not ideal for: Those looking for advanced massage technology or customizable settings for deeper relief.
- Temperature Range:95°F to 118°F
- Timer:Not specified
- Features:Bubble jets, simple controls
- Design:Collapsible
- Control Type:Manual buttons
Our verdict“Best for newcomers or seniors seeking an uncomplicated, space-saving foot spa experience.”
CARESKYpro Collapsible Foot Spa with Fast Heat UL-Listed Foot Soaking Tub
The CARESKYpro stands out for its high-pressure bubble jets and wide manual rollers, making it a solid choice for users who want targeted relief and deep tissue massage. Compared with the simpler OOAMBB, it offers more intense massage options, though it’s limited to foot-specific use and less versatile for other types of relaxation. The remote control and adjustable temperature enhance convenience, but its bulkier profile and corded operation could be drawbacks for those seeking portability. It’s best suited to users who prioritize strong, targeted foot therapy in a space-efficient package.
Pros:- High-pressure bubble jets for targeted massage
- Wide manual rollers for deep tissue relief
- Foldable design for storage
- Remote control for easy adjustments
Cons:- Limited to foot area, not suitable for full-body massage
- Requires corded power, limiting mobility
Best for: People with sore feet, requiring deep massage and targeted circulation enhancement.
Not ideal for: Travelers or those who want a multi-functional spa for full-body relaxation.
- Target Use:Foot
- Power Source:Corded Electric
- Features:Bubble jets, wide manual rollers, remote control
- Water Temperature Range:Not specified
- Design:Foldable
Our verdict“Ideal for users needing intense, targeted foot therapy with simple controls and space-saving storage.”
Large Collapsible Foot Spa Bath Massage with Heat, Electric Foot Soaking Tub
This spacious model caters especially to users with larger feet, up to men’s size 14+, offering generous room and multiple massage modes with 4D Tai Chi discs. Compared to smaller, more basic spas like the OOAMBB, it provides a richer massage experience with color touchscreen controls, remote operation, and extra features like a pumice stone and herb box. The larger footprint and electrical requirements make it less portable and more complex to set up, but it’s a clear choice for those who need ample space and varied massage options in their foot spa.
Pros:- Spacious design fitting up to men’s size 14+
- Multiple massage modes with 4D Tai Chi discs
- Includes pumice stone and herb box for enhanced foot care
- Color touchscreen and remote control for convenience
Cons:- Bulky when assembled, requiring ample space
- Requires electricity and water connection
- Controls may seem complex for casual users
Best for: Individuals with larger feet seeking a spacious, customizable massage experience.
Not ideal for: Users with limited space or those preferring simple, plug-and-play units without complex controls.
- Foot Space:Extra large, fits up to men’s size 14+
- Water Temperature Range:95°F to 118°F
- Timer:10–60 minutes
- Massage Modes:3 modes with 4D Tai Chi massage discs
- Additional Features:Pumice stone, herb box, blue light, touchscreen, remote control
- Foldable:Yes
Our verdict“Best suited for users with larger feet wanting extensive customization and extra foot care features.”
HOSPAN Collapsible Foot Spa with Heat, Bubble & Massage
This foot spa stands out for its adjustable temperature range and versatile features like bubble therapy, red light, and targeted shiatsu rollers, making it ideal for personalized foot care. Compared with the KNQZE Collapsible Foot Spa, it offers more massage options, but its manual roller system may feel less intense for some users. Its foldable design and safety features make storage and use convenient, though water capacity might be limited due to its collapsible nature. The inclusion of multiple therapies ensures a comprehensive spa experience, but the reliance on manual setup could be a drawback for those seeking quick, effortless use.
Pros:- Adjustable temperature and timer for tailored relaxation
- Effective massage rollers and shiatsu points target foot tension
- Foldable design simplifies storage and portability
- Includes bubble and red light therapy for stress relief
Cons:- Manual setup may be cumbersome for some users
- Limited water capacity due to foldable structure
Best for: Foot care enthusiasts who want customizable settings and space-efficient storage
Not ideal for: Users seeking intense massage or higher water capacity, as the collapsible design may limit volume and power
- Temperature Range:95°F-118°F
- Timer:10 to 60 minutes
- Massage Rollers:8 groups
- Shiatsu Massage Groups:4 groups
- Collapse Design:Yes
- Additional Features:Bubble, red light, heat
Our verdict“This model is best suited for those who value customizable features and space-saving convenience over maximum water capacity or intense massage.”
Medical King Foot Spa with Heat, Massage, and Jets
This foot spa offers a comprehensive set of features, including bubbles, vibration, and 14 removable rollers, making it ideal for deep muscle relief. Unlike the HOSPAN, which emphasizes customization and space-saving, the Medical King provides a variety of massage modes with a remote control, adding convenience. Its inclusion of a pedicure stone enhances foot care, but its bulkier profile might make it less suitable for small spaces or frequent travel. The multiple massage options can provide a more thorough experience, but the somewhat verbose description hints at complex operation that could challenge some users.
Pros:- Multiple massage options including bubbles, vibration, and rollers
- Removable rollers for targeted relief and cleaning
- Includes pedicure stone for foot care
- Portable design suitable for travel
Cons:- Could be confusing to operate due to many features
- Lacks specific size and weight details for portability assessment
Best for: Those seeking a versatile foot spa with multiple massage modes and portability for travel or home use
Not ideal for: Users seeking a compact, space-efficient model or simple operation without many features
- Heating:Adjustable with temperature control
- Bubbles:Oxygen bubbles for circulation
- Vibration:Yes
- Massage rollers:14 removable rollers
- Pedicure stone:Included
- Portability:Portable for home or travel
- Temperature range:3 levels
Our verdict“Ideal for users who want a feature-rich, portable foot spa with multiple massage options and foot care accessories.”
KNQZE Collapsible Foot Spa Bath with Heat & Remote Control, Bubble Massage, Temperature Control, Red Light (Black)
The KNQZE foot spa shines with its remote control, allowing easy operation from a distance, and safety features like hydroelectric separation and temperature protection. It offers multiple therapies, including heat, bubble massage, and red light, making it a solid choice for those who want a relaxing experience without manual adjustments. Unlike the HOSPAN, which focuses on customization, or the OOAMBB, which emphasizes portability, this model prioritizes safety and ease of use, though it provides limited detail on size and capacity. The controls may seem complex for some users, but the convenience outweighs that for many.
Pros:- Includes remote control for effortless operation
- Multiple massage and therapy features
- Collapsible design for easy storage
- Safety features like hydroelectric separation
Cons:- Limited detail on size and capacity
- Controls may be complex for some users
Best for: Users who value remote operation, safety features, and multiple therapy options in a compact foot spa
Not ideal for: Those seeking detailed specifications or a larger water capacity, as info is limited
- Timer:20 or 60 minutes
- Control:Remote control
- Color:Black
- Features:Heat, Bubble Massage, Red Light
- Safety:Hydroelectric separation, temperature protection
Our verdict“This foot spa is perfect for users prioritizing remote control, safety, and versatile therapies in a space-saving design.”
Collapsible Electric Foot Spa with Heat, Bubble, and Remote Control
This foldable foot spa combines ease of storage with advanced features like 3D massage balls targeting acupoints, adjustable heat, and bubble jets. It’s tailored for individuals who want a customizable, space-efficient device, but its focus on foot-specific massage limits its use for other body parts. The LED display and remote control add convenience, yet the remote’s precision aiming requirement could be frustrating for some. Compared to the OOAMBB, which offers more comprehensive accessories, this model emphasizes compactness and targeted foot relief at the expense of broader feature sets.
Pros:- Easy to fold and store in small spaces
- Multiple massage modes with adjustable temperature
- Remote control for convenient operation
- Includes 3D massage balls for targeted relief
Cons:- Remote control requires precise aiming
- Limited to foot massage only
Best for: People with limited space who want a foot spa with advanced massage and adjustable heat
Not ideal for: Users wanting a multi-function spa with full-body capabilities, as this is foot-specific
- Massage Balls:6 groups of 3D Tai Chi massage balls
- Temperature Range:95°F to 118°F
- Control:Remote control included
- Display:LED showing temperature
- Timer:10 to 60 minutes
- Foldable:Yes, folds in 2 seconds
- Height (Folded):5.5 inches
Our verdict“Best suited for space-conscious users seeking advanced foot massage with adjustable heat and remote control convenience.”
OOAMBB Collapsible Foot Spa Bath with Remote Control, Heat, Bubble, Timer
The OOAMBB foot spa combines multiple therapies—including adjustable heat, bubble jets, red light, massage rollers, and a pumice stone—making it ideal for comprehensive foot care. Its space-saving, foldable design matches that of the KNQZE, but it adds extra features like a pumice stone for callus removal and a calming red light. While its versatility is impressive, the multiple features may require some learning curve, and full water heating could take time. Compared with other models that focus on specific features, this one offers a balanced package for thorough foot relaxation and care in a portable package.
Pros:- Adjustable heat and multiple timer options
- Includes massage rollers and pumice stone for foot care
- Foldable, portable, and travel-friendly
- Calming red light enhances relaxation
Cons:- Limited to foot spa use, not suitable for full-body baths
- Requires batteries for remote control
Best for: Individuals seeking a multifunctional, portable foot spa with a focus on foot health and relaxation
Not ideal for: Users who want a simple, no-fuss spa with minimal features or maximum water capacity
- Water Temperature Range:95°F to 118°F
- Timer Options:10, 20, 30, 40, 50, 60 minutes
- Folded Height:4.74 inches
- Features:Heat, Bubble Jets, Red Light, Massage Rollers, Pumice Stone, Remote Control
Our verdict“This model is best for those wanting a comprehensive, portable foot spa with multiple therapies and foot-specific care tools.”
How We Picked
The products in this roundup were evaluated based on performance, usability, build quality, and value. Priority was given to how well each foot spa maintained consistent heat, the variety and effectiveness of massage features, and ease of operation. Durability and safety standards also played a role, especially for models with electrical components. The ranking reflects a balance between feature set and affordability, ensuring options suit different budgets and preferences. We focused on models that combine reliable heating with user-friendly controls, and considered customer reviews and expert insights to determine the most well-rounded choices.| foot spa with heat | Features |
|---|---|
| UNIFULL Collapsible Foot Spa B | Shiatsu rollers, bubble jets, collapsible design, water drain |
| Ranjova Collapsible Foot Spa w | — |
| OOAMBB Collapsible Foot Spa wi | Bubble jets, simple controls |
| CARESKYpro Collapsible Foot Sp | Bubble jets, wide manual rollers, remote control |
| Large Collapsible Foot Spa Bat | — |
| HOSPAN Collapsible Foot Spa wi | — |
| Medical King Foot Spa with Hea | — |
| KNQZE Collapsible Foot Spa Bat | Heat, Bubble Massage, Red Light |
| Collapsible Electric Foot Spa | — |
| OOAMBB Collapsible Foot Spa Ba | Heat, Bubble Jets, Red Light, Massage Rollers, Pumice Stone, Remote Control |
Factors to Consider When Choosing Foot Spa With Heat
Choosing the right foot spa with heat involves considering several key factors that influence comfort, durability, and value. Not all models are created equal, and understanding what to prioritize can help you avoid common pitfalls like overpaying for unnecessary features or selecting a device that’s hard to clean. The following sections highlight the most important considerations to help you make an informed decision.Heating Performance and Temperature Control
Reliable and adjustable heating is fundamental for a satisfying foot spa experience. Look for models with fast heat-up times and consistent temperature maintenance. Some units offer precise temperature controls, allowing you to customize your soak, while others rely on preset settings. Be aware that overly complex controls may complicate operation, so balance functionality with ease of use. Remember, a well-heated foot spa enhances relaxation and ensures your feet stay warm throughout the session.
Massage Features and Water Jets
Massaging elements like bubbles, shiatsu balls, or jets significantly elevate the spa experience. Consider what kind of massage your feet need—deep tissue, gentle relaxation, or a combination. More features often mean higher prices and potential maintenance concerns, so weigh their benefits against your budget. Also, check if massage features are adjustable to suit different preferences. Combining heat with targeted massage can improve circulation and reduce foot fatigue effectively.
Ease of Use and Controls
User-friendly controls, such as remote operation or simple buttons, make regular use more convenient. Some models have digital displays and timers, which can help you customize durations and temperature settings precisely. Avoid overly complicated interfaces that might frustrate less tech-savvy users. Additionally, consider how easy it is to clean the unit—models with removable components or smooth surfaces tend to be more hygienic and lower maintenance over time.
Build Quality and Portability
Durability varies across models, especially in collapsible designs that prioritize storage convenience. Look for sturdy materials and reliable seals to prevent leaks and ensure longevity. Portability is a plus if you want to move the spa easily or store it away when not in use. However, lighter, collapsible models might sacrifice some robustness, so weigh their convenience against durability for your usage style. A well-built foot spa minimizes the risk of electrical issues and extends the lifespan of your investment.
Price and Value
While budget models cover basic heating and massage features, investing a bit more can unlock advanced functions like stronger jets, timers, or remote controls. Consider what features genuinely enhance your experience and whether they justify the extra cost. Look for models that balance affordability with quality so you don’t compromise on safety or performance. Remember, a higher upfront investment may offer better durability and more satisfying features, saving money on repairs or replacements later.
Frequently Asked Questions
How long should I typically soak my feet in a foot spa with heat?
Most foot spas are designed for sessions of about 15 to 30 minutes, which is generally enough to relax muscles and improve circulation without overexposing your skin. It’s important to listen to your body and avoid prolonged soaks that can cause dryness or irritation. Using timers or adjustable settings can help you stick to safe and comfortable durations. Always follow the manufacturer’s recommendations for optimal and safe use.
Can I use a foot spa with heat every day?
Using a foot spa daily is possible, but moderation is advisable. Regular sessions can promote circulation and relaxation, especially if you have foot discomfort or circulation issues. However, excessive use might lead to skin dryness or irritation, particularly if your skin is sensitive. Incorporating moisturizing routines after use can help mitigate dryness. For most users, using the spa 2-3 times per week strikes a good balance between benefits and skin health.
Are collapsible foot spas as durable as non-collapsible models?
Collapsible foot spas prioritize storage convenience, but they often use lighter, less rugged materials, which can impact durability over time. High-quality collapsible models with reinforced seams and sturdy materials can last for years, but cheaper options may wear out faster or be more prone to leaks. If you plan frequent use or want a long-lasting device, investing in a more robust non-collapsible model might be better. However, for occasional use and storage ease, collapsible options work well when chosen carefully.
What safety features should I look for in a foot spa with heat?
Safety features like auto shut-off timers, overheating protection, and UL certification are essential for peace of mind. Auto shut-off prevents overheating or overuse, reducing the risk of accidents. Overheat sensors cut power if temperatures exceed safe levels, protecting your skin and the device. Certification from safety agencies indicates compliance with electrical safety standards. Always opt for models with these safety measures, especially if you’ll be using the spa frequently or if children may come into contact with it.
Is it better to choose a model with multiple massage options or a simpler design?
This depends on your preferences and budget. Models with diverse massage options—like bubbles, shiatsu balls, and jets—offer a more customizable and relaxing experience, but they often come at a higher price and may require more maintenance. Simpler models focusing on heat and basic massage functions tend to be more affordable, easier to clean, and reliable. If you enjoy varied massage sensations, investing in a feature-rich model makes sense; otherwise, a straightforward design may better suit your needs and reduce potential headaches.
Conclusion
For those seeking the best overall experience, the UNIFULL Collapsible Foot Spa offers a balanced combination of heat, massage features, and convenience. Budget-conscious buyers will appreciate the OOAMBB Collapsible Foot Spa for reliable performance at a lower price. If you want a premium option with powerful jets and advanced controls, the Medical King Foot Spa stands out. Beginners or infrequent users might prefer simpler models like the Ranjova Collapsible Foot Spa for ease of use. Finally, for portability and storage, collapsible designs like the KNQZE model deliver on convenience without sacrificing essential features. Your choice should align with your specific relaxation needs and budget constraints.
