Introducing the innovative OCA Ultra Comfort Water Cushion. Simply add this cushion to your chairs or wheelchairs to instantly improve user comfort and reduce compression for longer sitting. How it works: The cushion is filled with approximately 5.8 litres of water. This water will be absorbed into the foam, resulting in a gel-like texture. The valve is opened to release air that is trapped inside. The valve is then closed securely to prevent leakage.