Ultimate Arms Gear Heckler & Koch HK USP Compact Pistol Handgun Mount Weaver Picatinny Rail Adapter for Scope, Sights, Lasers, Lights & Accessories Constructed from Precision Machined Aircraft Grade Aluminum Alloy. Specifications: Length: 2.7" Inches. Weight: 1 oz. Easy to Install , No Gunsmitthing Required. Designed to Fit the Heckler & Koch HK USP Compact