10-Year 18 x 36 ft. Rectangle Pool Winter Cover With Water Tubes Includes qty 14 of 8ft double water tubes Pool cover color is Navy Blue Solid black underside for prevention of algae growth Resists acid, alkalis, salt, mildew, chlorine and temperatures up to -50 Degrees Fahrenheit Heavy-duty water tube loops are conveniently placed every 4 ft. to help hold tubes firmly in place