The R&R Targets Burris Fastfire sight mount replaces the Saiga-12 rear sight. Mine wouldn't drift out, but surrendered to the Dremel..
R & R Targets' page. They really don't show it except on their builds. Brownell's listing. 'Bout $14 cheaper with a C&R.
This doesn't show the underside, but basically those two hex screws hold a dovetail mount that fits (tightly) into the Saiga-12's rear sight dovetail and the center set screw holds it in place. The mount slides into the existing dovetail and a 10-32 set screw secures it (may be a 8-32, mine stripped out - which R