Numerous flashlights and lasers are compatible with a Picatinny or MIL-STD-1913 rail. In response GG&G has crafted an HK USP full-size flashlight mounting rail adapter that aligns with Picatinny Rail standards. This adapter fits snugly against the USP trigger guard allowing the rear rocker switches to be easily operated by the fire control finger or the thumb of the opposite hand. Constructed with solid billet 6061-T6 aircraft-grade aluminum it grips the existing USP light rails securely enough to maintain zero on laser sights.