Use air pillows to help keep the pool cover clean and also to help with protecting your pool from ice damage by providing a place on the pool surface where ice can expand to. Air pillow 4'x15' Winter Cover Air Pillows For Above-Ground Pools This rugged vinyl pillow absorbs freezing waters pressure and helps protect your pool walls by creating a high spot on your winter cover from the center of your pool. The Air Pillow reduces excess rain, snow, and leaves from accumulating on your winter cover which could colapse your winter cover or even your pool walls. The size of the pillow refers to width and length. The pillow is either square or rectangular depending on the size. We offer air pillows in 4x4, 4x8 or 4x15. The 4' x 8' air pillow may be substituted by our shipping department with two (2) of the 4' x 4' air pillows if we are out of stock; and also the 4' x 15' air pillow may be substituted by our shipping department with two (2) of the 4' x 8' air pillows if we are out of stock.