Tri-Zone Pocket Coil System – Includes 3 zones of support at 1166 coils (head/torso/foot) with thick 2-mm spring coils for extra lumbar support in the torso zone. Foam Encased Edge Guard – 4-inch hard foam perimeter for added edge/sitting support, with a ¼-inch quilted border. Tight Top Comfort – 2-inch ultra soft foam and 1-inch high density support bottom. 1-inch viscose foam and double fiber pad for added lumbar support. Bamboo Woven Fabric – Stretchable silver bamboo woven fibers with spider pattern for natural comfort and breathability.