Production of reference 3525 was launched in 1939. The model was made in stainless steel, yellow and pink gold as well as steel and gold (yellow and pink). Different versions in regard to case material and dial layout are illustrated in 100 Superlative Rolex Watches by John Goldberger, pp. 96-107, and in I Cronografi Rolex - La Leggenda, Pucci Papaleo Editore, pp. 162-192.