Officially called the Medal For Faithful Service in the National People's Army Reserve, these medals were awarded to soldiers who served honorably for 18-24 months in the Nationa's Peoples Army (NVA). 
The front of the medals translates to "Reservist of the National People's Army" while the backside translates to "For the Protection of the Workers and Farmers' Power" and features the East German coat of arms. 
 
There were gold and silver medals (gold was for 10+ years of service while silver was for 2-10 years of service).
Only the bronze medals are available. 
 
These all come with the original white plastic case. Some will be cracked or have broken pieces. But all of the medals are in good shape.