The exclusive Charter Club by Sealy Mystic Bay Extra Firm Mattress features trusted Sealy quality with an upgraded high coil density Pocketed Spring Support System that has reinforced Steel Quantum Edge Coils. Its heavy duty pocketed springs reduce movement, allow for an undisturbed side to side sleep while layers of Isotonic Memory Foam and Gel Foams offer pressure relief and comfort, and a stretch knit cover with Cooling Fibers and Lurex Accents to help you sleep better.