This camera is the fourth model of Nippon Kogaku's rangefinders, after the “1”, the “M”, and the “MS”. It was produced in approximately 35,000 copies until 1954. The "S" comes from Synchronization which is present by two contacts for magnesium flash. The Nikon S is still in 24 X 34 mm format and it will be necessary to wait for the Nikon S2 to finally switch to 24 X 36 mm. Some very rare copies in black finish. Some very rare ones also have 8 digits as the serial number.