In my opinion it's a rather bad fake, as this design is not correct for a Gustav Brehmer Erdkampfabzeichen. In addition the reverse setup is also incorrect for this maker and the makers mark itself does not convince me at all, it looks downright wrong and quite puny. The photos aren't the best but it is evident to me that the quality of the details just aren't there either. It doesn't look like a zink badge I feel either.
As usual Kenneth is correct in his analysis, the badge is a fake. One thing I would add to the above and useful to note, is that Brehmer didn't make a three rivet Erdkampfabzeichen.
Looking for LDO marked EK2s and items relating to U-406.....
The guys are right, also the detail of the clouds around the eagle dont check out to me
"In all my years as a soldier, I have never seen men fight so hard." - SS Obergruppenfuhrer Wilhelm Bittrich - Arnhem