Genesis 900 King Size Hardside Waterbed Mattress 20 Year Warranty 12 Layer Total Mid-Body Support System With convoluted foam layer. 24 Mil Premium Aqua Marine Vinyl. Molded Conch Shell Design Top with Phase II Air Release Valve. L-Seam Construction with Recessed Black Bottom 4-Way Hook & Eyelet Tethered Support System. Multi-Laminate Dual Color Molded Reinforced Corners.