The Casper Select 12" Hybrid Medium-Firm Mattress in King size is a Costco-exclusive all-foam mattress designed to provide balanced support and pressure relief. This 12-inch mattress features four layers of premium CertiPUR-US certified foam, including breathable open-cell foam to prevent heat trapping, high-density memory foam for cushioning, zoned transition foam with three distinct zones (softer at shoulders and feet, firmer at the hips), and a durable support foam foundation for stability.

The zoned support system is engineered to keep the spine neutrally aligned during sleep, making it particularly well-suited for back sleepers and many side sleepers. The mattress measures 76" W x 80" L x 12" H and weighs 104 pounds. It offers solid motion isolation for couples, decent edge support for an all-foam design, and responsive comfort without excessive bounce.

The cover is a soft, stretchy blend of polyester, upcycled cotton, rayon, and lycra that is hand-sewn and zippered for easy removal. All foams are made without ozone depleting chemicals and have low VOC emissions for indoor air quality (less than 0.5 parts per million), regulated by the Consumer Product Safety Commission. The mattress comes compressed in a box and requires 24-48 hours to fully decompress, with any new mattress smell dissipating within a few days in a well-ventilated room. It includes a 10-year limited warranty and works with any hard flat surface including box springs, solid platforms, or slatted bases. To extend the life of the mattress, rotate it 180 degrees every six to eight months.