A portable stadium seat for use over existing bleachers or stadium seats has a rigid frame on which an inflatable cushion is provided. The seat frame may have pivotally connected leg and head rest portions. The seat cushion may have a head rest, a lumbar support, a back rest, a seat portion and armrests...http://www.google.es/patents/US4781413?utm_source=gb-gplus-sharePatente US4781413 - Portable stadium seat
