The S sets were a class of electric multiple unit operated by Sydney Trains and its predecessors from 1972 up until 2019. The carriages were of stainless steel, double deck construction. The class operated in New South Wales, Australia and was the oldest in the Sydney Trains fleet until June 2019, when they were replaced by the Waratah Series 2 (B Set) trains. Prior to their retirement, the S Sets were the last class in the entire fleet that was not air-conditioned, earning them the nicknames “Tin cans” and “Sweat Sets”. They were also nicknamed “Ridgys” because of their fluted stainless steel appearance; they shared this nickname with similar looking K sets and C sets.