The Pool Mate Professional-Grade Charcoal In-Ground Pool Cover protects your pool during harsh Winter conditions. This professional-grade, premium polyethylene cover blocks out any dirt and debris throughout the Winter. The Professional-Grade Charcoal Cover prevents algae growth by blocking UV rays from entering your pool in the Winter. Pool owners who use a Pool Mate Professional-Grade Charcoal 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. Please order by pool size and add to the length and/or width if you have steps or a buddy-seat. 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,Äôs longevity. Includes water tube loops to be used with water tubes, sold separately. This professional-quality premium cover has heat sealed seams and is built to last longer. Includes premium binding around perimeter of cover. The Pool Mate Professional-Grade Charcoal In-Ground Pool Cover comes with a 20-year warranty.