The Economy pool cover is a solid winter cover. Solid pool covers do not allow water to pass through their material. This winter cover is intended to be used during the off-season. Please order by your pool size, as the overlap goes beyond the pool size listed. This cover includes a 3 ft. overlap. If you have a very large top rail, please consider a larger pool size. The Economy pool cover has a 7 x 7 scrim. Polyethylene weighs 2.2 oz./yd2. The blue topside of this cover is coated to prevent damage caused by the sun's ultra-violet rays and the bottom side is black to prevent algae growth. 2 grommets are placed on center every 4 ft., with these grommets, you should use the included winch and all-weather cable to secure your pool cover. For extra securing, cover clips and cover wrap (both sold separately) are suggested for pool closing. No other method of installation is recommended. The cover should be able to comfortably float on the pool water without excessive stress. Includes a 8 year warranty.