Looks like cheap knockoff of fab defense to me. - FAB Defense Magazine Well Grip for M16/M4/AR15

I had purchased the real Fab Defense well grip prior to purchasing these. The real Fab Defense has a window for the serial number, these don't. I tried these on 4 different mil spec lowers and it didn't properly fit any of them. Would require removing material to make it fit and if you mess up there goes your return. I would steer wide away from these cheap knockoffs. I find it interesting they only show the side without the window so you won't notice the difference. Shame on you.