http://www.airsplat.com/Itemdesc.asp?ic=AC-MNT-P668&eq=&Tp=
Like wraith said it's a cast "pot metal" leapers mount, I have one on a MP5 loaner, it's OK, but there are much better ones out there it's big and clunky.
Look its a bird its a plane, no its just my broken aeg flying all over the place.
www.cheaperthandirt.com <- The usually have some pretty good stuff for cheap