Vissco orthopaedic back rest PC0121 universal designed to increase comfort by aligning your spine and supporting correct posture unlike traditional "l" shaped chairs, the "s" shaped frame of the obusforme molds your spine into proper anatomical alignment features molded, impact resistant, lightweight polycarbonate frame * durable polyurethane foam protects frame and provides cushy comfort use together with any obusforme seat backrest is orthopaedically designed for sitting comfort.