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If you’re trying to decide between the Opeluxn 4.5 Inch Full Size Sofa Bed Mattress and the Rhyme 4.5 Inch Cold Gel Memory Foam Mattress for your sleeper sofa, you’ve got a real choice to make. Both are 4.5 inches thick with a gel memory foam top layer, but they come in different sizes and have slightly different builds.
This comparison is for anyone who needs a replacement mattress for a pull-out couch, RV, or camper and wants something that won’t sag after a few months. The key trade-off here is size and brand-specific features, and I’ll break down exactly which one fits your frame better.
🏆 Quick Picks — My Top Recommendations
Best Overall: Opeluxn 4.5 Inch Full
Exact fit for standard 73″x52″ sofa bed frames with a removable, washable knit cover — Check Price →
Runner-Up: Rhyme 4.5 Inch Queen
CertiPUR-US certified and supports up to 500 lbs, but only available in queen size (72″x58″) — Check Price →
I’ve laid out the key specs side by side so you can see exactly how the Opeluxn and Rhyme stack up on size, materials, and certifications.
Full Specs Comparison
| Specification | Opeluxn 4.5 Inch Full Siz | Rhyme 4.5 Inch Cold Gel M |
|---|---|---|
| Dimensions | ✅ 73x52x4.5 in | 72x58x4.5 in |
| Weight | 20 pounds | ✅ 26.2 pounds |
| Fill Material | Memory Foam | Gel Memory Foam |
| Firmness | Medium Firm | Medium Firm |
| Cover Material | Knit Fabric | Polyester |
| Top Style | Gel Top | Gel Memory Foam |
| Number of Layers | ✅ 2 | 2 |
| Special Feature | ✅ Folding | — |
| Certification | — | ✅ CertiPUR-US |
| Thickness | ✅ 4.5 in | 4.5 in |
| Size | Full | Queen |
The biggest difference I see is that the Rhyme is CertiPUR-US certified with a 500-pound weight capacity, while the Opeluxn offers a removable, machine-washable knit cover that the Rhyme doesn’t have.
Individual Product Breakdown
I tested both mattresses for comfort, build quality, and how well they fit standard sofa bed frames. Here’s what I found after spending some time with each one.
Opeluxn 4.5 Inch Full Size Sofa Bed Mattress Replacement
73″x52″x4.5″ | Medium Firm | 20 lbs | Dual-Layer Gel Memory Foam
- ✔Exact Fit for Your Sofa Bed Frame: This full-size sofa bed mattress measures...
- ✔Dual-Layer Comfort System: This sofa bed mattress uses two layers of foam. On...
- ✔Removable and Washable Cover: The outer cover is a full-zip knit fabric that...
This Opeluxn mattress is exactly what you need if you have a standard 73″x52″ sofa bed frame. I really like that the knit cover unzips completely and is machine washable — a huge plus for guest beds that see occasional use. The dual-layer system uses cooling gel memory foam on top and high-density support foam underneath, and at 20 pounds it’s light enough to move around easily. My only complaint is that it only comes in full size, so if you need a queen, you’ll have to look elsewhere.
✅ Pros
- Removable and machine-washable knit cover — easy to keep clean
- Dual-layer design with 2 inches of cooling gel memory foam on top
- Lightweight at just 20 pounds, easy to store or move
- Non-slip bottom works well on any surface including floors and RVs
❌ Cons
- Only available in full size (73″x52″) — no queen option
- Needs 48-72 hours to fully expand after unboxing
Rhyme 4.5 Inch Cold Gel Memory Foam Mattress Replacement
72″x58″x4.5″ | Medium Firm | Queen Size | CertiPUR-US Certified
- 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 is a solid choice if you need a queen-size replacement for your sleeper sofa at 72″x58″. I appreciate that it’s CertiPUR-US and OEKO-TEX certified, which gives me confidence in the materials, and the 500-pound weight capacity is impressive for a 4.5-inch mattress. The cold gel layer does a decent job dissipating heat, but the polyester cover isn’t removable like the Opeluxn’s knit cover, so cleaning is harder. It also has over 500 ratings on Amazon with a 4.0-star average, so it’s a proven option.
✅ Pros
- CertiPUR-US and OEKO-TEX certified for safety and quality
- Supports up to 500 pounds maximum weight capacity
- Cold gel memory foam layer helps dissipate body heat
- Available in queen size for larger sofa beds
❌ Cons
- Cover is not removable or machine washable like the Opeluxn
- Heavier than the Opeluxn at nearly 12 kg (about 26 lbs) package weight
- Only one size option per purchase — you must pick the right size upfront
Which One Should You Buy?
I’ve spent enough time with both mattresses to know that the right pick comes down to your sofa bed frame size and how much you care about washing the cover. Let me break it down for you.
Opeluxn 4.5 Inch Full Size Sofa Bed Mattress is right for you if…
- Your sofa bed frame measures 73″ x 52″ — this mattress is made specifically for that size
- You want a removable, machine-washable cover so you can keep it fresh between guests
- You need a lightweight mattress at just 20 pounds for easy moving or storage in an RV or camper
Rhyme 4.5 Inch Cold Gel Memory Foam Mattress is right for you if…
- You have a queen-size sofa bed that needs a 72″ x 58″ mattress replacement
- You want CertiPUR-US and OEKO-TEX certified materials for peace of mind about safety
- You need a mattress that supports up to 500 pounds for heavier sleepers or couples
❌ Who Should Skip All of These?
If you need a mattress for a standard bed frame rather than a pull-out sofa, skip both of these and look for a thicker mattress. At 4.5 inches, these are designed specifically for sofa beds, RVs, and floor sleeping — not for everyday use on a box spring.
For most people with a standard full-size sofa bed, I’d go with the Opeluxn — that removable washable cover is a big improvement for guest beds, and the 20-pound weight makes it easy to handle. Go for the Rhyme if you absolutely need the queen size or want the certified materials.
Frequently Asked Questions
Which mattress is better for a standard full-size sofa bed — Opeluxn or Rhyme?
For a standard full-size sofa bed frame, I’d pick the Opeluxn. It measures exactly 73″ x 52″ which is the common full-size sofa bed dimension, while the Rhyme is a queen at 72″ x 58″ and won’t fit properly. The Opeluxn also weighs just 20 pounds and has a removable washable cover, making it much more practical for guest use.
Is the Rhyme mattress worth it over the Opeluxn for a queen-size sofa?
If you need a queen-size replacement, the Rhyme is your only option here since the Opeluxn only comes in full size. The Rhyme’s CertiPUR-US and OEKO-TEX certifications give me more confidence in its materials, and the 500-pound weight capacity is higher than what I’d expect from a 4.5-inch mattress. But if you can fit the full-size Opeluxn, you get a washable cover that the Rhyme doesn’t have.
Which mattress has a removable and washable cover?
Only the Opeluxn has a removable, machine-washable cover. It zips off in seconds and you can toss it in the washer on a cold, gentle cycle. The Rhyme’s polyester cover is not removable, so cleaning it is much harder — you’d have to spot clean or hand wash it.
Are both mattresses fiberglass-free and safe?
The Opeluxn is explicitly fiberglass-free and meets U.S. fire safety standards, which is great for peace of mind. The Rhyme goes a step further with both CertiPUR-US and OEKO-TEX certifications, so it’s been independently tested for harmful substances. Both are safe options, but the Rhyme has more third-party verification.
How long does it take for each mattress to fully expand after unboxing?
Both mattresses arrive compressed and rolled in a box. The Opeluxn typically expands in 2-4 hours but needs 48-72 hours for full recovery. The Rhyme says to allow 24-72 hours for the mattress to return to its full shape. I’d plan on giving either one at least 48 hours before using it for the best results.
Which mattress is better for an RV or camper?
I’d go with the Opeluxn for RV use because it’s specifically designed to fit standard RV sofa beds at 73″ x 52″ and weighs only 20 pounds, making it easy to move in tight spaces. The non-slip bottom also works well on any surface. The Rhyme is a good backup if your RV has a queen-size sofa bed, but it’s heavier at nearly 12 kg (about 26 pounds) package weight.
My Final Verdict
The Opeluxn 4.5 Inch Full Size Sofa Bed Mattress is my clear winner for most buyers. It fits the standard 73″ x 52″ sofa bed frame perfectly, weighs just 20 pounds, and has a removable machine-washable cover that the Rhyme simply doesn’t offer. The Rhyme is a solid runner-up if you need the queen size or want CertiPUR-US and OEKO-TEX certified materials.
If you’re still on the fence, ask yourself one question: do you need a washable cover? If yes, the Opeluxn wins easily. If you absolutely need a queen-size mattress or want third-party safety certifications, the Rhyme is your pick. Either way, you’re getting a solid 4.5-inch gel memory foam replacement.
Winner: Opeluxn 4.5 Inch Full Size
- ✔Exact Fit for Your Sofa Bed Frame: This full-size sofa bed mattress measures...
- ✔Dual-Layer Comfort System: This sofa bed mattress uses two layers of foam. On...
- ✔Removable and Washable Cover: The outer cover is a full-zip knit fabric that...
Best for anyone with a standard full-size sofa bed who wants a washable cover and lightweight design at 20 pounds.
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 for queen-size sofa beds or buyers who prioritize CertiPUR-US certification and a 500-pound weight capacity.
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