Neoprene was not the only material used in early wetsuits, particularly in Europe and Australia. The Pêche-Sport "isothermic" suit invented by Georges Beuchat in 1953 and the UK-made Siebe Gorman Swimsuit were both made out of sponge rubber. The Heinke Dolphin Suit of the same period, also made in England, came in a green male and a white female version, both manufactured from natural rubber lined with stockinet. As early as July 1951, underwater hunters in Australia were experimenting with a natural rubber wetsuit "of a 'wrap on' variety, which does not set out to be 100% waterproof (but it is claimed that) the leakage of water through it is so slow that body warmth under it is maintained for hours." By May 1953, the Bondi underwater equipment manufacturer Undersee Products was already distributing this singlet-like design commercially to Australian sporting goods stores, where it was described thus: "Made from heavy sheet rubber, the Sealskin suit is most effective when worn over a football jersey. When jersey becomes wet, rubber holds it firmly against body and thus warmth is generated. Water circulation automatically stops and body warmth builds up in moisture-laden jersey. The Seaskin suit provides both underwater insulation and above-water wind protection."