The Serta iComfort Blue 300 Firm Mattress has a smooth top quilt design that is breathable and thin, and this lets the comfort layers conform better to the curves of your body. Critical comfort materials include TempActive Max Gel Memory Foam, a high quality memory foam with TempActive temperature regulation technology integrated right into the surface to achieve immediate as well as long term cooling. A layer of EverCool Fuze Gel Memory Foam ensures consistent pressure relief to help minimize tossing and turning and encourage deep REM sleep. A layer of Serta Support Foam works together with the Deep Reaction Memory Foam to create an underlying feel that is solid. Support to the back is provided with the help of the Ultimate Edge Foam Support Core. This core delivers a wonderful blend of contouring and support, it helps reduce motion transfer, and it's adjustable base friendly. The edge support system ensures consistency in comfort, even when sleeping to the edge.