A spa cover is assembled from two or more molded foam sections. The sections may be molded from polystyrene, polyethylene, or a mixture of polystyrene and polyethylene. Panels are molded into the sections along mating edges, which panels cooperate to align the sections. The sections further include latches...http://www.google.co.uk/patents/US7490368?utm_source=gb-gplus-sharePatent US7490368 - Spa cover
