12-Year 21 ft Round Pool Winter Cover With Cover Clips All seams are heat-sealed (not sewn) to prevent water from seeping through the cover Triple laminated poly-constructed inner scrim is topped by a premium weather resistant top coating Comes complete with heavy-duty vinyl coated cable and winch Pool cover color is dark green with a black underside to inhibit algae growth Includes 35 cover clips that secure cover to top rail, preventing wind from getting under the cover