Royal solid winter cover for 28-feet round above ground pool (cover is 31-feet round) 5-mm, blue on black triple laminated polyethylene with heat sealed seams for added strength. Edges incorporate a sewn-in polypropylene cord for reinforcement. Aluminum grommet spaced every three feet. Deluxe aluminum cable winch and vinyl coated steel lock-down cable included. 8-year limited warranty, 1-year full.