No serial #

F. W. Breithaupt & Sohn (Kassel) is an old German company with a long tradition which delivered many compass types to the industry (mines) and the armies.This compass originally was called "Model COKIL" (COmpass KILometer) because is was equipped with a map reader (curvimeter) 

It was and still is being manufactured in China. Different versions were issued to the Vietcong troops during the US  vs. Vietnam war and to the People's Republic of China's Army.

The signs on the rose read:

- under the red star: Type 51

- in the clinometer sector:
 company name: Shanghai Yonghong Instruments

The rose has a 6000 mils division

On the back there is a curvimeter (map reader)  (a device for measuring the length of curves such as on a map) It has  four scales.