Choose from the available size options. Cool gel memory foam and innerspring mattress. 13.5 in. thick hybrid mattress. ActivPur, HD, and AirCool gel memory foam layers. Individual pocketed coils. Conforming back support and freedom of movement. Optional box spring in choice of available sizes, heights. 10-year manufacturer's warranty. With the conforming back support of individually wrapped pocketed coils and gel-infused memory foam with cooling technology, the Beautyrest Platinum Hybrid Crestridge 13.5 in. Plush Mattress offers the best of both worlds. This plush, hybrid mattress offers freedom of movement and precision pressure point relief. It boasts an InfiCool HD surface that moves heat away from your body as you sleep. Make the mattress complete by adding the optional box spring foundation, which is offered in a choice of available sizes and heights. This mattress comes in your choice of available size option. Size: Full.