The Swimline 18 Foot Round Above Ground Winter Swimming Pool Cover is great for keeping your pool in good condition during the cold, winter months, but it will also make getting your pool back into shape in the spring much easier. This pool cover is made of laminated polyethylene sheeting woven with thick, high density polyethylene stitching, which ensures superior tensile strength and durability. It has also been treated to provide maximum resistance to damaging ultraviolet rays.For the long life of your pool, choose the Swimline 18 Foot Round Above Ground Winter Swimming Pool Cover.ACC44The Swimline Air Pillow is the ultimate companion to any winter pool cover. This Swimline air pillow will keep your pool and cover safe from ice in the winter months because it helps to keep water off of your pool cover. The pillow also helps to make sure your cover won't freeze to your pool water during the cold off season.When inflated, it measures 4 x 4 feet big. It pushes your pool cover up off the water's surface so the water won't freeze to your pool cover.Keeps water off the top of your pool cover and preserve your cover with the Swimline Air Pillow.