Shanghai 7's series - Rare 7420 SS7's Automatic Prototype

Rarest Shanghai 7's series, automatic version of "Tonji". As per the Shanghai Light Industry Bureau web page, It was introduced by Shanghai 1st Watch Factory on 1974, the factory Movement code is "ZCSH". It carries a 25j movement = a normal 19J 7221 movement + 6j automatic device.




It comes with the original 19J calander watch dial casue it's a prototype

caseback with "Si (prototype)" marked under the Shanghai Logo