This package includes 2 winter covers and 2 air pillows.The Swimline 24 Foot Round Above Ground Pool Winter Cover keeps your pool in tip top shade during the off seasons. It prevents debris from getting in so when the season rolls back around, you can get back into the swim of things easier and with less maintenance.It's constructed of laminated polyethylene sheeting and woven with thick, high density stitching to ensure strength and durability year after year. It features a ratchet and cable system with high tested vinyl coated cable and provides maximum protection.The 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 8 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.