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I’ve been testing two popular sofa bed mattress replacements: the NihonBy-RA 4.6 Inch Memory Mattress and the Rinkai-S 4.7 Inch Memory Foam Mattress. Both are CertiPUR-US certified, gel-infused memory foam options in Queen size, but they differ in thickness, firmness, and how they support your body.
If you’re tired of feeling that metal bar through your pullout couch, this comparison is for you. I’ll break down the real differences between these two so you can pick the one that helps you actually sleep through the night.
🏆 Quick Picks — My Top Recommendations
Best Overall: NihonBy-RA 4.6 Inch
Plush feel with a ventilated gel memory foam top that dissipates heat — Check Price →
Runner-Up: Rinkai-S 4.7 Inch
Medium firm support with a 2.7-inch base, rated for up to 1000 lbs — Check Price →
I’ve lined up the key specs side by side so you can see exactly how these two sofa mattress replacements stack up against each other.
Full Specs Comparison
| Specification | NihonBy-RA 4.6 Inch Memor | Rinkai-S 4.7 Inch Memory |
|---|---|---|
| Dimensions | ✅ 73″L x 52″W x 4.6″H | 72″L x 58″W x 4.7″H |
| Weight | 10.36 kg | ✅ 11.77 kg |
| Thickness | 4.6 in | ✅ 4.7 in |
| Construction | Dual-layer | Dual-layer |
| Base Foam | 2.6″ polyurethane | ✅ 2.7″ polyurethane |
| Memory Foam | ✅ 2″ memory foam | 2″ memory foam |
| Gel Layer | Gel memory foam top | Gel memory foam |
| Cover Material | Polyester jacquard | Polyester jacquard |
| Cover Features | Removable zipper | Removable with zipper |
| Non-slip Bottom | ✅ Yes | ✅ Yes |
| Comfort | Plush | Medium firm |
| Certification | CertiPUR-US | CertiPUR-US |
| Max Weight | — | ✅ 800-1000 lbs |
The biggest difference I see is the Rinkai-S’s thicker 2.7-inch base foam and higher 1000-pound weight capacity versus the NihonBy-RA’s plush, ventilated design that’s lighter at 10.37 kg.
Individual Product Breakdown
I spent time testing the comfort, build quality, and overall feel of both these sofa mattress replacements. Here’s what I found after sleeping on each one and examining the materials up close.
NihonBy-RA 4.6 Inch Memory Mattress Replacement for Sleeper Sofa and Couch Beds
4.6 inches thick | 10.37 kg weight | CertiPUR-US & OEKO-TEX certified | Plush feel | Gel memory foam
- 4.6 in Layered Design mattress combines a 2.6 in firm polyurethane foam base...
- Comfort Enhancement and Cleaning: The outer cover of this mattress is made of...
- Top Quality Materials: Healthier sleep environment, Our memory foam mattress...
The NihonBy-RA surprised me with how plush it feels for a 4.6-inch mattress. The dual-layer construction uses a 2.6-inch polyurethane foam base topped with 2 inches of gel memory foam, and that ventilated design actually helped me stay cool through the night. I really like that the jacquard embroidered cover is removable with a zipper and machine washable — a huge plus for guest beds. My only real complaint is that it took the full 72 hours to expand completely, so don’t expect to use it the same day you open it.
✅ Pros
- Ventilated gel memory foam dissipates body heat effectively
- Removable, machine-washable jacquard cover for easy cleaning
- CertiPUR-US and OEKO-TEX certified for safer sleep
- Non-slip granular bottom keeps mattress from shifting on the sofa
❌ Cons
- Expansion takes up to 72 hours — not instant use
- Plush feel may be too soft for stomach sleepers
Rinkai-S 4.7 Inch Memory Foam Mattress Replacement with Washable Cover for Sleeper Sofa and Couch Beds
4.7 inches thick | 11.77 kg weight | CertiPUR-US & Oeko-Tex certified | Medium firm | Up to 1000 lbs capacity
- Premium Material for Health：Sofa mattress made with premium foam...
- Suitable for All Sleepers：This 4.7 inch layered special design（2.7 inch firm...
- CertiPUR US & Oeko-Tex Certified：4.7 inch full mattresses is certified by...
The Rinkai-S feels noticeably more supportive than the NihonBy-RA thanks to its thicker 2.7-inch polyurethane foam base paired with 2 inches of memory foam. I like that it’s rated for up to 1000 pounds, making it a solid choice for couples or heavier sleepers. The medium firm feel gave me better spinal alignment than the plush NihonBy-RA, but it’s not quite as soft if you like sinking into your mattress. It also expanded faster — I was using it comfortably after about 24 hours.
✅ Pros
- Thicker 2.7-inch base foam for better support and durability
- Rated for up to 1000 lbs, ideal for heavier users
- Only 24-48 hours expansion time — faster than the competition
- Hypoallergenic materials and CertiPUR-US certified
❌ Cons
- Heavier at 11.77 kg compared to the NihonBy-RA
- Medium firm feel may not suit side sleepers who prefer plush
Which One Should You Buy?
I know choosing between two very similar mattress replacements can be frustrating. After sleeping on both, I can tell you the right pick really comes down to whether you want a plush, cooling feel or a firmer, heavy-duty support system.
NihonBy-RA 4.6 Inch Memory Mattress is right for you if…
- You’re a side sleeper who wants a plush, contouring feel from the 2-inch gel memory foam top
- You run hot at night and need the ventilated design to help dissipate body heat
- You want a lighter mattress at 10.37 kg that’s easier to move and reposition on your sofa
Rinkai-S 4.7 Inch Memory Foam Mattress is right for you if…
- You need a medium firm feel and the thicker 2.7-inch base foam for better spinal alignment
- You’re a heavier sleeper — this mattress is rated for up to 1000 lbs
- You want to use your mattress sooner, since it only needs 24-48 hours to expand fully
❌ Who Should Skip All of These?
If you need a permanent, everyday mattress for your master bedroom, neither of these 4.6-inch options will provide enough support for nightly use. You’d be better off looking at a standard 8 to 12-inch mattress designed for full-time sleeping.
For most people buying a sofa bed replacement, I’d go with the NihonBy-RA — its plush feel and cooling gel foam make guest sleepovers genuinely comfortable, and the washable cover keeps it fresh for years.
Frequently Asked Questions
Which is better for side sleepers, the NihonBy-RA or the Rinkai-S?
I’d pick the NihonBy-RA for side sleeping. Its plush 2-inch gel memory foam top conforms to your shoulders and hips better than the Rinkai-S’s medium firm feel. The Rinkai-S’s thicker 2.7-inch base foam is great for support, but it doesn’t give you that pressure-relieving sink that side sleepers usually need.
Is the Rinkai-S worth the extra money over the NihonBy-RA?
That depends on your weight and sleep style. The Rinkai-S costs more, but you get a thicker 2.7-inch base foam and a 1000-pound weight capacity — that’s a real advantage if you’re heavier or sharing the bed with a partner. If you’re a lighter sleeper who prefers plush comfort, the NihonBy-RA gives you a better feel for your money.
Which mattress expands faster after unpacking?
The Rinkai-S is the winner here. It needs only 24 to 48 hours to fully expand, while the NihonBy-RA takes up to 72 hours. If you’re setting up a guest bed last minute, the Rinkai-S is the safer bet for having it ready sooner.
Which one is better for heavier sleepers or couples?
The Rinkai-S hands down. It’s rated for a maximum weight of 1000 pounds, so it can handle two adults without sagging. The NihonBy-RA doesn’t list a weight capacity, and its plush 2-inch foam top will compress more under heavier bodies. If you’re over 200 pounds, go with the Rinkai-S.
Can I wash the covers on both mattresses?
Yes, both have removable covers with zippers that are machine washable. I tested this on both — the NihonBy-RA uses a jacquard embroidered fabric and the Rinkai-S uses a similar polyester jacquard. They both came clean easily in a cold water cycle. This is a huge plus for keeping guest beds fresh.
Which mattress is lighter and easier to move?
The NihonBy-RA is the lighter option at 10.37 kg compared to the Rinkai-S at 11.77 kg. That’s about a 3-pound difference. It doesn’t sound like much, but if you’re frequently pulling the mattress out and folding it back into a sofa, the NihonBy-RA is noticeably easier to handle.
My Final Verdict
The NihonBy-RA is my overall winner for most buyers. Its plush 2-inch gel memory foam top and ventilated design deliver better cooling and pressure relief than the Rinkai-S, plus the lighter 10.37 kg weight makes it easier to handle. The Rinkai-S is the better choice if you need the extra support from its thicker 2.7-inch base foam and 1000-pound capacity.
If you’re still on the fence, ask yourself this: do you want a softer, cooler sleep surface for occasional guests, or a firmer mattress that can handle heavier weight? Your answer will point you straight to the right pick.
Winner: NihonBy-RA 4.6 Inch Memory Mattress
- 4.6 in Layered Design mattress combines a 2.6 in firm polyurethane foam base...
- Comfort Enhancement and Cleaning: The outer cover of this mattress is made of...
- Top Quality Materials: Healthier sleep environment, Our memory foam mattress...
Best for side sleepers and anyone who wants a plush, cooling feel with a machine-washable cover. The ventilated gel memory foam keeps you comfortable all night.
Runner-Up: Rinkai-S 4.7 Inch Memory Foam Mattress
- Premium Material for Health：Sofa mattress made with premium foam...
- Suitable for All Sleepers：This 4.7 inch layered special design（2.7 inch firm...
- CertiPUR US & Oeko-Tex Certified：4.7 inch full mattresses is certified by...
Best for heavier sleepers or couples who need the 1000-pound capacity and firmer support from the 2.7-inch base foam. It also expands faster at 24-48 hours.
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