Tianjin 天津 ST5 Sea-Gull 海鸥 IV - China Railways

Model : Sea-Gull 海鸥
Manufacturer : Tianjin Watch Factory (天津手表厂)
Year of Production: 1970s
Case Diameter :
Weight w/o strap: g
Movement Model : ST5B (19 jewels) 
Type : Hand Wind

This is a Sea-Gull watch for China Railways the logo of which is on the dial. See wiki page here. However, it is not the railroad standard watch but a normal watch powered by ST5 movement engraved with decorative stripes. The movement has the date calendar but with no hacking function. It is protected with an anti-magnetic shield and has a date calendar with no hacking function. The crown is signed with Sea-Gull logo.

The caseback is the standard Sea-Gull case back. But from the images found in internet, China Railways Sea-Gull usually has the standard caseback engraved with serial number and also the name of the issuing railways office. So, the caseback may not be well the original one.

Other watches produced by Tianjin Watch Factory: