The only one I know of that makes what you want is Phillips Gunsmithing in Cibolo, Texas. Phil fits them to your barrel/rib for a perfect fit. He can be contacted at 210-313-5988. I don't believe there is an aftermarket blinder like this on the market as Phil makes his from scratch as I understand. Last time I checked the cost to put one on your gun was $35.00.......Hope that helps....Dan Thome (Trap2)
I've never seen one that screwed on except for Harlan Campbell's. He ground the teeth off a 3-inch piece of a hacksaw blade and screwed it to the side of his rib with tiny machine screws. I don't know how he drilled the second hole in it.