Full Mattress in a Box 12 in Medium-Firm Mattress - Cool, Supportive

In this review the Full Mattress in a Box is presented as a practical mattress for sleepers who want a balance of support and pressure relief without chemical flame barriers. The reviewer finds it best for everyday adult sleepers, teens, and children using bunk or daybeds because of its 12 in thickness and medium-firm feel. The single biggest reason to consider this mattress is the combination of gel-infused memory foam for cooling and a medium-firm profile that aims to relieve pressure while keeping the spine supported.

Key Features

• Material and cover: A 92% cotton, 8% polyester rib fabric cover provides a soft, breathable surface that feels natural against skin.
• Medium-firm support: The mattress is tuned to a 6-7 out of 10 firmness level to offer a balance of lumbar support and pressure relief for most sleep positions.
• Gel-infused memory foam: Cooling gel is integrated into the foam to help dissipate heat while preserving body-conforming comfort.
• CertiPUR-US certified foam: All foams meet safety and emissions standards, reducing concerns about long-lasting off-gassing or harmful materials.
• Fiberglass-free fire barrier: The inner cover uses a flame-retardant textile approach, avoiding fiberglass and related health risks.

Who It's For

This mattress suits adults and young sleepers who prefer a medium-firm feel that keeps the spine aligned without sinking too deeply. It is particularly apt for platform beds, daybeds and bunk frames where a predictable thickness of about 12 in is needed and where a neutral smell on arrival is desired.

Those who need a very plush, soft surface or a very firm orthopedic mattress may want to look elsewhere, as some shoppers noted the mattress can feel firmer than expected. Also measure your bed frame carefully: a few users reported size and fit issues with nonstandard frames.

Pros & Cons

Pros

• Comfortable, medium-firm feel that works for many sleep positions and ages.
• Cooling gel in the memory foam helps reduce heat retention compared with plain foam.
• CertiPUR-US foams and a cotton-rich cover reduce off-gassing and provide a natural surface.
• Fiberglass-free flame barrier offers safer handling and fewer irritation concerns.

Cons

• Perceptions of firmness vary; some find it firmer than the advertised medium-firm level.
• A small number of customers reported minor size/fit differences versus expectations for certain beds.

Specifications

Size	Full (double)
Thickness	12 in
Cover material	92% cotton, 8% polyester
Comfort level	Medium-firm (6-7 of 10)
Foam features	Gel-infused memory foam, CertiPUR-US certified
Fire barrier	Fiberglass-free inner cover (textile-based)

Our Verdict

The Full 12 in mattress is a sensible choice for shoppers who want a medium-firm, supportive mattress with cooling gel and safer flame protection. It offers good value when you prioritize a neutral smell on delivery, natural-feeling cover fabric, and CertiPUR-US foam standards; just confirm frame fit and expect a firmer feel if you prefer plush mattresses.

Frequently Asked Questions

Will this mattress sleep hot?
The gel-infused memory foam helps dissipate heat and generally sleeps cooler than non-gel memory foam.

Does it have a strong new mattress smell?
No; CertiPUR-US foams and the cover construction mean minimal off-gassing for most users.

Is the mattress safe without fiberglass?
Yes; the mattress uses a fiberglass-free inner cover as the flame barrier to avoid fiberglass-related irritation risks.