This commercial-quality polyethylene cover blocks out any dirt and debris throughout the Winter. The Commercial-Grade Slate Blue Cover prevents algae growth by blocking UV rays from entering your pool in the Winter. Pool owners who use a Pool Mate Commercial-Grade Slate Blue Pool Cover and close their pool with the proper Winterizing chemicals will have a clean pool in the spring that will be easy to open. It is always recommended to open your pool by mid to late May. This cover features a 5 ft. overlap. Overlap is additional material beyond the size of your pool. The cover should be able to float comfortably on the water. Ordering a larger size cover and putting the extra material inside the pool can help increase the pool cover???s longevity. Includes water tube loops to be used with water tubes, sold separately. Includes premium binding around perimeter of cover. This commercial-quality lightweight cover has heat sealed seams and is built to last longer.