The Premier pool cover is a extra heavy-duty 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 4 ft. overlap. If you have a very large top rail, please consider a larger pool size. The Premier winter cover features a extra heavy-duty scrim count (threads per square inch). The Premier pool cover has a extra heavy-duty 12 x 12 scrim. Extra heavy-duty polyethylene weighs 3.26 oz./yd2. Both the scrim count and material weight are the best indicators of the overall strength and durability of your pool cover. Includes a extra heavy-duty binding around the perimeter of the cover that prevents against wear and tear, helps keep grommets in place and adds to the life expectancy of this cover. The slate 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 premium 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 15 year warranty.