The 4000 Hybrid Firm mattress features iComfort’s most innovative cooling and support technologies. Carbon Fiber Memory Foam paired with the UltraCold System help channel heat away from your body. Our exclusive Air Support Foam contours to your body and helps relieve aches and pains caused by pressure points, while the 1025 iComfort Hybrid Support System with BestEdge Foam Encasement provides durable support from edge to edge. Serta iComfort 4000 14-in Firm Twin Extra Long Hybrid Memory Foam/Coil Blend Mattress with Boxspring Included in White | 500800918-9920