A nice authentic Bulgarian People's Republic medal here, awarded for 15 Years of Impeccable Service to Bulgaria while serving in the military construction troops. 
 
Until 1989, the Construction Troops were called up to serve their compulsory military service, mainly from ethnic minorities (Turks and Gypsies), so-called "unreliable Bulgarians" (former political prisoners/repressed) and those with limited fitness for combat service. The conscripts underwent initial military training, including rifle training (after which they do not have access to weapons), as well as training in construction specialties. A security platoon in the unit, usually ethnic Bulgarians, were the only soldiers with access weapons - usually at checkpoints, weapons depots, and detention centers.