Han spa cover Foam thickness is 4" 2" tapered which allows rain, ice and snow runoff. Foam density available : 1 lb1.5 lb2lb. Up to 12 colors for you to select; Stitching is all reinforced with internal reinforcement at high stress and problem areas. The highest grade marine grade vinyl with uv & mildew inhibitors exceed astm g 155 and astm g 21 test ; We use a steel reinforcement stiffener down the center for added strength. Cold cracking resistance, burn resistance, abrasion resistance (wyzenbeek test method) Exceeds all astm standards for hot tub (spa) covers. Finished off with a 3 year warranty.