Five-Zone Quantum Coil System – Includes 5 zones of support at 936 coils (head/torso/foot/side supports) with thick 1.8-mm spring coils for extra lumbar support in the torso zone and 2.2-mm coils in side support zones. Quantum Coil Edges – Strong, narrow diameter caliber steel coiled edges, with a ¼-inch quilted border. Ideal for adjustable bases. Euro Top Comfort – 3-inch medium soft foam euro top with double fiber pad for added lumbar support. Bamboo Woven Fabric – Stretchable bamboo woven fibers for natural comfort and hygiene.