The Robelle Defender winter cover is a heavy-duty, UV-resistant polyethylene solid winter cover for above ground pools. This cover includes a four-foot overlap, making this cover easier to secure to your pool than other pool covers. Please order by pool size, as the overlap goes beyond the pool size listed. If you have a very large top rail, please consider a larger pool size. The cover should be able to comfortably float on the pool water without excessive stress. The top of this cover is Sandstone, & the bottom side is black to prevent algae growth. The Robelle Defender winter cover features a heavy-duty 12 x 12 scrim. This cover is constructed with a heavy-duty polyethylene material that weighs 3.26 oz./yard2 both the scrimcount & material weight are good indicators of the strength of your pool cover. A cover with a higher scrimcount & heavier material, like the Robelle Defender winter cover, will last longer than inferior covers. Two grommets are placed on center every four'. with these grommets, you should use the included winch & all-weather cable to secure your pool cover. The Robelle Defender winter cover includes a twelve-year warranty.