Ultimate Arms Gear Tactical Dovetail 3/8" 11mm To Weaver - Picatinny 7/8" Rail Adapter Mount - Includes Set Of 4 Rails 4 Rails Included - Each Rail Measures Approximately 2" Long Made Of Aircraft Grade Aluminum Alloy With Black Matte Finish Simple To Install - Just Attach To Your 3/8" (11mm) Dovetail Rail To Transform It Into A 7/8" Weaver Picatinny Rail Allows You To Attach All Your Weaver Picatinny 7/8" Base Accessories : Scopes, Lights, Lasers, Rings Etc. Perfect For Pistols - Paintball - Airsoft - .22 Rifles Or Other Dovetail Based Weapons