Purchased from a reputable HK parts seller in Germany who said this is a factory HK prototype. Marked WW for Obendorf. This sheet steal with canvas bag brass catcher is refinished HK black. A rail on the left side fits into the receiver groove with a latch to secure into the right groove. Canvas bag is blach, holds about 20 spent casings and does show a little wear. $210 shipped. Email me at firstname.lastname@example.org for photos. Thanks for taking time to read.