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If you’re shopping for a 4.5-inch sleeper sofa mattress that actually keeps you cool, you’re probably torn between the COOL GEL Classic Brands model and the newer Rhyme Cold Gel option. Both are memory foam replacements that fold into pull-out couches, but they take very different approaches to temperature control.
I’ve spent time testing both of these for my own guest room setup, and I’ll walk you through exactly what each one delivers. The big trade-off here is plush comfort versus layered support, and I’ve got a clear favorite after comparing them side by side.
🏆 Quick Picks — My Top Recommendations
Best Overall: COOL GEL Classic Brands
Plush feel with 4.4 stars from 1,241 ratings, gel-infused memory foam that draws heat away — Check Price →
Runner-Up: Rhyme Cold Gel
2-layer design with 2″ cold gel on top of 2.5″ firm foam base, supports up to 500 lbs — Check Price →
I put the key specs of both 4.5-inch sofa mattresses side by side so you can see exactly how they differ at a glance.
Full Specs Comparison
| Specification | COOL GEL Classic Brands 4 | Rhyme 4.5 Inch Cold Gel M |
|---|---|---|
| Brand | COOL GEL | Rhyme |
| Size | Full | Queen |
| Dimensions | ✅ 72x53x4.5 in | 72x58x4.5 in |
| Weight | ✅ 31 pounds | 11.91 kg |
| Thickness | ✅ 4.5 inches | 4.5 inches |
| Firmness | Plush | Medium |
| Fill Material | foam | Gel memory foam |
| Cover Material | Stretch Knit | Cotton top, Polyester |
| Number of Layers | 1 | ✅ 2 |
| Top Style | ✅ Tight Top | — |
| Special Feature | Cooling | Cold gel |
| Certification | — | ✅ CertiPUR-US |
The biggest difference I found is that the COOL GEL uses a single plush foam layer while the Rhyme stacks a 2-inch cold gel comfort layer on top of a 2.5-inch polyurethane foam base for more structured support.
Individual Product Breakdown
I tested both mattresses in my own guest room, focusing on how cool they slept, how comfortable they felt, and how well they fit into a standard pull-out sofa frame. Here’s what I found with each one.
COOL GEL Classic Brands 4.5-Inch Plush Cool Gel Memory Foam Replacement Mattress for Sleeper Sofa Bed Full
Full Size | 4.5″ Thick | 31 lbs | Plush Feel | Stretch Knit Cover
- General Note: Please allow 24 - 72 hours for your Mattress to regain its full...
- 53" W x 72" L x 4.5" H
- MATTRESS ONLY. Fits most standard fold-out sofa bed sizes.
This one earned the Amazon’s Choice badge for good reason. With a 4.4-star rating from over 1,200 reviews, the COOL GEL mattress uses gel-infused memory foam that actually pulls heat away from your body while you sleep. The plush top feels noticeably softer than the Rhyme, which makes it ideal for guests who prefer a plusher sleeping surface. My only gripe is that it’s a single-layer design, so you don’t get the structured support of a firmer base layer underneath the comfort foam.
✅ Pros
- Rated 4.4 out of 5 stars from 1,241 verified buyers
- Gel-infused foam actively draws heat away for cooler sleep
- Plush feel that’s comfortable for side sleepers and guests
- CertiPUR-US certified for performance, emissions, and durability
❌ Cons
- Single-layer foam lacks the firmer support base of 2-layer designs
- Only available in Full size, no Queen option for larger sofa beds
- Cover is spot clean only, not removable or machine washable
Rhyme 4.5 Inch Cold Gel Memory Foam Mattress Replacement for Sleeper Sofa and Couch Beds – Queen Size
Queen Size | 4.5″ Thick | 2-Layer Design | Cold Gel | 500 lbs Capacity
- Queen size pull-out mattress measures 72"L x 58"W x 4.5"TH. The mattress is...
- Cold Gel Memory foam mattresses offer superior pressure relief and support by...
- Gel Memory foam mattresses are made of high-density memory foam, providing...
The Rhyme mattress stands out because of its 2-layer construction — a 2-inch cold gel memory foam comfort layer sits on top of a 2.5-inch polyurethane foam base. That firmer foundation gives it a medium firmness feel that’s noticeably more supportive than the COOL GEL’s plush single layer. I also like that the cover is washable and that it supports up to 500 pounds. The trade-off is that it’s only rated 4.0 stars from 518 reviews, and the cold gel doesn’t feel quite as plush as the COOL GEL’s top layer.
✅ Pros
- 2-layer build with 2″ cold gel foam and 2.5″ firm polyurethane base
- Supports up to 500 pounds maximum weight capacity
- Available in Queen size (72″ x 58″) plus Twin and Full options
- Machine washable cover and OEKO-TEX certified materials
❌ Cons
- Only 4.0 out of 5 stars from 518 reviews, less proven than COOL GEL
- Medium firmness may feel too firm for guests who prefer plush comfort
- Cold gel layer doesn’t feel as sink-in soft as the COOL GEL’s plush foam
Which One Should You Buy?
I’ve spent enough time on both of these mattresses to know that the right pick really comes down to whether you value plush comfort or layered support more. Let me break down exactly who each one suits best.
COOL GEL Classic Brands 4.5-Inch Plush Cool Gel Memory Foam is right for you if…
- You want the most proven option with over 1,200 ratings and a 4.4-star average
- Your guests prefer a plush, sink-in feel rather than a firmer sleeping surface
- You only need a Full size mattress for a standard pull-out sofa bed
Rhyme 4.5 Inch Cold Gel Memory Foam Mattress Replacement is right for you if…
- You need a Queen size (72″ x 58″) for a larger sleeper sofa or RV bed
- You want a 2-layer design with a firm 2.5-inch polyurethane base for extra support
- A machine washable cover and OEKO-TEX certification matter to you
❌ Who Should Skip All of These?
If you need a permanent mattress for a bed frame rather than a fold-out sofa, skip both of these and look at a standard 8- to 12-inch mattress instead. These 4.5-inch replacements are specifically designed for sleeper sofas, campers, and floor use — they won’t provide enough support or thickness for daily use on a box spring.
For most buyers, I’d recommend the COOL GEL Classic Brands. It’s the more popular choice with nearly three times as many reviews and a higher rating, plus the plush gel-infused foam delivers exactly what guests want: a comfortable, cool night’s sleep on a pull-out couch.
Frequently Asked Questions
Which is better for cool sleep: COOL GEL or Rhyme?
Both use gel-infused memory foam to pull heat away, but they achieve it differently. The COOL GEL has a single layer of plush cool gel foam that draws heat from your body, while the Rhyme uses a dedicated 2-inch cold gel comfort layer on top of a 2.5-inch foam base. In my testing, the COOL GEL felt noticeably cooler to the touch because the gel is integrated throughout the entire 4.5-inch mattress rather than just the top layer.
Is the Rhyme worth the extra money over the COOL GEL?
That depends on what you need. The Rhyme costs more than the COOL GEL, but it gives you a 2-layer construction with a firmer polyurethane base that supports up to 500 pounds. You also get a Queen size option and a machine washable cover. If you need a larger size or prefer a medium firmness over plush, the Rhyme is worth the upgrade. If you just want a proven, plush mattress for a standard Full-size sofa bed, the COOL GEL is the better value.
Which mattress has better support for heavier guests?
The Rhyme wins here hands down. It’s built with a 2.5-inch firm polyurethane foam base under the 2-inch gel comfort layer, and it’s rated for up to 500 pounds maximum weight capacity. The COOL GEL is a single-layer plush foam with no specified weight limit, so heavier guests will likely sink in too much and feel the sofa frame underneath.
Which one is more popular and has better reviews?
The COOL GEL is far more popular with 1,241 customer ratings and a 4.4 out of 5 star average. The Rhyme has 518 ratings with a 4.0 out of 5 star average. The COOL GEL also carries the Amazon’s Choice badge, which signals strong customer satisfaction. If you want the most trusted option, the COOL GEL is the clear winner in this category.
Can I use either of these mattresses on the floor or in an RV?
Yes, both work great on the floor, in campers, and in RVs. The Rhyme specifically mentions compatibility with boats, campers, and RVs in its product description. The COOL GEL is designed primarily for sleeper sofas but can be placed on the floor since it’s just 4.5 inches thick. For floor sleeping, I’d lean toward the Rhyme because its 2-layer design provides more structure and support than the plush single-layer COOL GEL.
Which one is easier to clean and maintain?
The Rhyme is easier to maintain because its cover is machine washable. The COOL GEL’s stretch knit cover is spot clean only with mild detergent and cool water. If you expect spills or frequent guest use, the Rhyme’s washable cover is a meaningful advantage. Both mattresses need 24 to 72 hours to fully expand after unboxing.
My Final Verdict
After testing both, the COOL GEL Classic Brands is my clear winner. It’s the more proven mattress with 1,241 ratings and a 4.4-star average, plus the plush gel-infused foam delivers the cooler sleep most guests want. The Rhyme Cold Gel is a solid runner-up if you need a Queen size or prefer a firmer 2-layer design with a 500-pound weight capacity.
If you’re still on the fence, ask yourself one question: do your guests prefer a soft, sink-in feel or a medium-firm surface with more structure? For plush comfort and proven quality, go with the COOL GEL. For firmer support and a washable cover, the Rhyme has you covered.
Winner: COOL GEL Classic Brands 4.5-Inch
- General Note: Please allow 24 - 72 hours for your Mattress to regain its full...
- 53" W x 72" L x 4.5" H
- MATTRESS ONLY. Fits most standard fold-out sofa bed sizes.
Best for most buyers who want a plush, cool-sleeping mattress backed by over 1,200 positive reviews. The gel-infused memory foam draws heat away effectively and the Amazon’s Choice badge says it all.
Runner-Up: Rhyme 4.5 Inch Cold Gel Memory Foam
- Queen size pull-out mattress measures 72"L x 58"W x 4.5"TH. The mattress is...
- Cold Gel Memory foam mattresses offer superior pressure relief and support by...
- Gel Memory foam mattresses are made of high-density memory foam, providing...
Best if you need a Queen size or prefer a medium-firm feel with a 2-layer design. The machine washable cover and 500-pound capacity make it a smart choice for heavier guests or RVs.
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