It is indeed a Weaver, but I don't recommend it unless you never intend to take it back off. The clamp is "slipped on" neatly scratching the lovely surface of the Redhawk's finish. Instructions even warn you of this, after you've bought it, of course! (nobody I knew had one) If I ever want it back to stock, it'll likely take a professional to get that finish right again. Strong as hell though.