These military chronographs equipped many air force pilots from various nations, but it is best known for its use by the West German Luftwaffe. From the '60s to the '70s, the "Bund".
Appeared over the years with different types of dial the present lot is called 3H, just for the red circled coat of arms over the 6 hours indicating the luminous material used, (Hydrogen-3), or more known as tritium.