Tri-Zone Pocket Coil System – Includes 3 zones of support at 1102 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 ½-inch medium soft foam euro top with double fiber pad for added lumbar support. Viscose Fabric Top – Stretchable, embossed viscose fabric for additional soft comfort feel.