Waterproof 600d Polyester Square Hot Tub Cover Outdoor Spa Covers 90x90in Black Brand new, never used, but opened out of the box. General to fit hot tub size up to 90?(L)x 90?(W). NOTE: This cover can not be used by itself without an insulated hard cover under it. Made of 600D polyester canvas complex with waterproof backing. Tough enough to keep rain, hail, snow, dust, leaves and bird droppings away. Well-made structured air vents at two sides keep ventilation, prevent the cover from being blown away, also keep your furniture dry and in good condition. Heavy duty elastic cords allows adjustment for a tight and easier fit, especially during high winds and severe weather. Full coverage design avoids the furniture exposure in the sun makes your hot tub always look like new.