A chair for providing sacral support including a seat, a backrest, a flexible support member and a sacral support member. The backrest has a frame with a generally central opening. The membrane is formed from an elastic material connected to the frame and extends across the central opening. A sacral...http://www.google.com.au/patents/US7878591?utm_source=gb-gplus-sharePatent US7878591 - Sacral support member for seating
