8 firm mattress

Most listings offer standard U.S. sizes — Twin, Full, Queen, and King. Some listings also note availability in Twin XL and California King, and a few mention multiple thickness options.

Many 8-inch models include cooling features such as gel-infused memory foam or gel particles embedded in the foam to help regulate body temperature and dissipate heat.

They typically use memory-foam or gel layers and a layered construction that contours to the body to relieve pressure points and absorb motion, which reduces motion transfer.

Common fill materials include memory foam (including 100% memory foam), various polyfoams, gel-infused memory foam, and polyurethane or high-density foam.

Listings commonly reference CertiPUR-US certification for foams and OEKO-TEX Standard 100 for fabrics; one listing also references the federal flammability standard 16 CFR Part 1633.

Descriptions vary across listings and include 3-, 4-, 5-, and 6-layer constructions.

They are described as compatible with most frames and foundations, including metal bed frames, box springs, upholstered platform beds, slatted frames, bunk beds, adjustable bases, and even placement directly on the floor.