Pressure relief for wheelchair patients is improved by use of a relatively higher density foam, such as 2.4 pounds per cubic foot or above and a 25 percent ILD characteristic of at least about 50 pounds, together with independently acting cube shaped segments. The segments have predetermined respective...http://www.google.com.au/patents/US5568660?utm_source=gb-gplus-sharePatent US5568660 - Wheelchair cushion and cover
