The IWC 'Skinny' Ingenieur SL Automatic 3505 was introduced in 1983 as a smaller alternative to the 'Jumbo' SL of 1976. This watch has a case of 34.00mm, which houses an ETA-based self-winding movement in the form of caliber 375.Reference IW3505-12 has a stainless steel case with yellow gold (14k) bezel and a matching bracelet. The dial is Black.