This is for the version listed as made for the 91 rifles, on Choate's site (tho I didn't mention that-everywhere I went they were listed seperately from the mp5 choate folders). It fits to the back of the original backplate/black cap, with a hard rubber(?) buffer replacing the original metal buffer in the stock. The recoil rod is still there on the original ptr 32 back cap.If you are talking about the mp5 Choate folding stock , it isn't designed for that application. the ptr 32s are the same backend as a 91. And the recoil rod is built into the rear sheet metal back cap.