General Use Extreme Comfort Wheelchair Back Cushion with Lumbar Support, 20" Innerspring Mattress heavy equipment and the bother GEN4880A heavy equipment and the bother of frequent refilling associated with traditional oxygen therapy systems The General Use Back Cushion uses a Durable Masonite board which is secured on the back of the unit and prevents swaying in sling back wheelchairs The Extreme Comfort General Use Wheelchair Back Cushion with Lumbar Support is perfect for patients who need additional support for their back or would just like extra comfort The General Use Back Cushion's back is made of a special non slip vinyl which prevents the unit from sliding when the use is moving