GLI Aquacover Classic 21-Feet Round Solid Winter Cover System for Above Ground Pools GLI Aquacover Classic Actual Cover Size 24-Feet Round Solid Winter Cover System for Above Ground Pools Made from tough polyethylene fabric which is the toughest, most durable material available; it won't crack, split or tear from the cold Lightweight, easier to put on and take off the pool than heavier, bulkier vinyl covers; takes up less room to store Double folded self edge, double stitched with water, chemical and sun resistant thread Hold-Tite reinforced seams which lasts longer and it won't rip, fray or come apart