The 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 preserves your cover with two Swimline air pillows.