Stammkp.Pz.Aufkl.Ers.u. Ausb.Abt.4 EKM

The tag or 'Erkennungsmarke' shows overall signs of wear. It belonged to a soldier who served/was draften in the Stammkompanie Panzer Aufklärungs Ersatz und Ausbildungs Abteilung 4. This unit was formed in October 1941 as Kradschützen Ersatz Bataillon 4. It trained an supplied soldiers (since summer 1942) for Aufklärungs Abteilung  (mot) 580 which was part of the 90.leichte-Afrika-Divsion. In mid April the abteilung was renamed into Panzer Aufklärungs Ersatz und Ausbildungs Abteilung 4. From July 1943 on it trained and supplied soldiers for Panzer Aufklärungs Abteilung 21 which was formed in France. This unit saw action during the Normandy Campaign and was later moved to the east. 

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 as there was a shortage of (front)soldiers.
The dog tag is broken, but complete and solid. The 'O' on both parts of the tag stands for the soldier's bloodtype.