It is just a "clip", could have been for anything. One use I could think of is holding his helmet by the strap. Possibly an MG canister for the 34 or 42. The use of the spring loaded clip is endless. I have a uniform with that style clip and the same maker mark on it (DRGM)hanging inside from a strap. I found out it was put through a slit in the interior and hung outside the uniform for a dress bayonet.
http://f1.pg.photos.yahoo.com/bc/mg4...anger+Hook.jpg
Later......................Bruce