Thanks, a friend sent the photo asking about the marking and I was focused on the marking rather than the rivets. I apologize for the misidentification, your information I will pass this along to him.That is not a WW1 frog, more real Reichswehr unit or early Wehrmacht, Artillerie Regiment nr.1?1 question remains the 2.Abteilung how is noted. Grz could be for Grenz, unfortunally we dont known how is dated the frog? and the picture is too small. The alu rivets speaks for period 1936-40.