Pool Mate 1-3748-02 Heavy-Duty 4-foot x 8-foot Winterizing Air Pillow for Above Ground Swimming Pools, 2-Pack Absorbs stress created by ice build up Reduces the build-up of rain water, leaves and snow on your cover Using additional pillows will protect your pool if one fails Pillow will pop before the ice damages your pool Simply inflate the pillow and place it under your cover