Stam.Kp.Gren.E.Btl.(mot.)53 EKM

The dog tag or 'Erkennungsmarke' shows normal signs of wear. The Infanterie Ersatz Bataillon 53 was formed in the summer of 1939  in Naumburg. It trained and supplied soldiers for Infanterie Regiment 53 which was part of the 14.Infanterie-Division. 
In November 1942 the bataillon was renamed into Grenadier Ersatz Bataillon (motorisiert) 53, but the motorized aspact was dropped in July 1943. 
In 1944, by then it was Grenadier-Ersatz- und Ausbildungs-Bataillon 53, trained and supplied soldiers for Grenadier Regiment 425 465 and 475. In April 1945 the bataillon was mobilized as Grenadier Ausbildungs Bataillon 53 and became part of the 463.Ausbildungs-Division which fell under the 4.Panzerarmee.
The 'O' on both parts of the tag stands for the soldier's bloodtype.

A Stammkompanie was a unit that trained the soldiers. Often the soldiers of this kompanie were soldiers who had frontline experience and/or where no longer fully usable on the front due to injuries. Of course this changed later in the war and they also where put into action (in the last months of the war) as there was a shortage of (front)soldiers.