2.Kp./Schtz.Ers.Btl.(m)196 EKM

The dog tag or 'Erkennungsmarke' shows signs of wear. The bataillon was formed in August 1939 as Infanterie Ersatz Bataillon 196 in Cottbus and in October 1941 it was renamed into Schützen Ersatz Bataillon 196. It trained and supplied soldiers for Infanterie Regiment 196 which was part of the 68.Infanterie-Division. 
In July 1942 it was renamed Panzer Grenadier Ersatz Bataillon 196 and it still supplied soldier for the, by then renamed, Grenadier Regiment 196. The bataillon was mobilized in April 1945 and served as a combat unit as part of Panzer-Ausbildungs-Verband Thüringen, was absorbed by the 2.Panzer-Division and was put into action for the Battle of the Rhineland.

Soldiers of a Schützen Regiment are the ones you often see in the Sd.Kfz's (halftracks) and are part of a Panzer Regiment/Division.
The 'O' on both parts of the tag stands for the soldier's bloodtype. 
Interesting Panzer infanterie related dog tag which is not easy to find.