Get cool and comfortable sleep with one mattress, the Serta Perfect Sleeper Cobalt Calm Mattress. We designed our king size Serta Perfect Sleeper mattress with a classic quilted top and an 850-coil density system that delivers zoned comfort and pressure relief. This upgraded model comes with antimicrobial protection, a cooling mattress cover and cooling gel memory foam layers. The PillowSoft Aire memory foam layer delivers both breathability and comfort. Our cooling gel memory foam provides even more cooling and comfort while our support foam relieves pressure points. The upgraded innerspring system delivers long-lasting support. This Serta Perfect Sleeper has an extra firm feel and feels sturdy. At the top of our 12" mattress, we have our cooling mattress cover that keeps you feeling refreshed throughout the night. Browse our innerspring mattresses at Serta. | Serta Perfect Sleeper Cobalt Calm King Mattress - Innerspring | Extra Firm