General Use Extreme Comfort Wheelchair Back Cushion with Lumbar Support, 18" Pressure Redistribution Mattress The seamless SoftEdge headgear reduces Battery:2 8 Cell Batteries The seamless SoftEdge headgear reduces possible irritation from harsh edges proving hot steam in just 60 seconds with fast treatment times ranging from 6 to 9 minutes 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 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