Stamm Kp.Pz.Pi.Ers. Batl.208 EKM

The tag or 'Erkennungsmarke' shows overall normal signs of wear. It belonged to a soldier who served or was drafted in the Stammkompanie Panzer Pionier ersatz Bataillon 208. This bataillon was formed in April 1940 in Rathenow as Pionier Ersatz Bataillon 208. It trained and supplied soldiers for Pionier Bataillone 39,79,200,208,218.  In October 1942 the bataillon was renamed Panzer Pionier Ersatz Bataillon and now also supplied soldiers to Panzer-Pionier-Bataillone 13,23,32,39,59,79,93.
It's not entirely sure but the bataillon was probably used, in January 1945, to form Panzer Pionier Bataillon Rathenow and in April 1945 the bataillon was absorbed with 5 companies into Panzer Ausbildungs Verband Ostsee. 
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 'A' on both parts of the tag stands for the soldier's bloodtype.