I don't even think that is German WW2 construction. The "gan 41" markings, which I can't enlarge, are likely fake. It's definitely not for an MP.40 and it is highly unlikely that it is German WW2 construction, or even WW2 for that matter. See: http://www.k98kforum.com/showthread.php?320-Fakes-Die-stamp-library
There were only two issue magazine pouches for the MP.40. The six mag pouch is shown in the link below, plus other variants of the three cell pairs. These are the only issue pouches: http://www.mp40.nl/index.php?page=original-pouches