This is a 4 foot x 8 foot air pillow made with standard 16 gauge vinyl. Air pillows are designed for use on aboveground pools to raise the cover up so that water will run off. They can also be used on inground winter pool covers. The vinyl air pillow absorbs the freezing water's pressure and helps protect your pool walls. They also prevent water that has turned to ice from adding pressure to your pool walls. In addition, they will help keep the water clear and clean until you are ready to open the pool in the springtime.It is important to note that when inflating the air pillows, the manufacturer does not recommend the pillows be filled to capacity. Follow all manufacturers' recommended fill percentage and instructions.