This mount fits:
Ruger Blackhawk
Ruger Super Blackhawk
Ruger Redhawk
GP100 (with adjustable rear sights)
GP100 Match Champion

Once installed it enables you to mount a red-dot or pistol scope to your revolver.

This mount does not fit:
Ruger Flattop Revolvers
Ruger Super Redhawk

Due to manufacturing variances in the Ruger's top strap, this mount may require the pad on the bottom to be filed to fit the rear sight cut out.

This rail mounts using the hole from your rear sight, but also requires you to drill and tap two additional holes in your receiver if your gun is not already drilled and tapped.

Rail Type: One Piece Picatinny
Machined from: Domestic 6061 T6 Extruded Aluminum
Finish: Matte Silver Anodizing
Overall Length: 4.3"
Height: .4" (Top of Receiver to Top of Picatinny)
Weight: 2 oz.
Quick Disconnect Ring Compatible: No
Ambidextrous: Yes
Torque Specs: 20 in/lbs
Mounting Hardware: #8-40 X 3/8 SHCS & 6-48 X 9/16 SHC Screws and T-10 Bit Included