This pretty rare version of Heuer Carrera was issued to the Belgian Air Force in 1970 - it has a manual wind movement, although Heuer just issued the very first automatic chronographs a year earlier.
The caseback is stamped with FAé marking for Force Aérienne Belge, NATO reference number and the issue unique serial number.
It also has Heuer serial number stamped between the lugs.
The watch is sometimes falsely called 'Carrera Congo', although it couldn't have been issued to Belgian forces in Congo as they left the country almost 10 year earlier.
The Valjoux 7733 movement works fine and keeps good time, chrono functions working properly, starting, stopping and resetting to zero - it has been serviced in March 2019.
The watch is overall in very good condition, the case has been professionally refinished, but all edges kept sharp - please see pics.