Arisaka Defense Vertical Grip Picatinny Black Anodized. It features a radiused profile at the top which tapers to meet the mounting surface on the handguard giving a low-profile feel and ergonomic comfort. The grip is hollow with no end-cap and has no externally visible clamp hardware. Instead it uses a unique recoil lug that extends from inside the part providing a secure rattle free lockup. The recoil lug and patched mating screw are captured and cannot fall out when the Vertical Grip is removed from the Picatinny rail. Please note: Extending the recoil lug to tighten the grip on a picatinny rail is accomplished by turning the 7/64" Allen wrench counterclockwise when looking into the open cavity of the vertical grip. To retract the recoil lug the 7/64" Allen wrench is turned clockwise. It is recommended to extend/retract the recoil lug before installing the Vertical Grip on a picatinny rail to gain familiarity with how it functions. Specifications for Arisaka Defense Vertical Grip Picatinny: Manufacturer: Arisaka Defense Color: Black Finish: Anodized Gun Rail: Picatinny Features of Arisaka Defense Vertical Grip Picatinny: CNC Machined from 6061-T651 Aluminum Package Contents: Arisaka Defense Vertical Grip Picatinny Arisaka Defense Vertical Foregrip Black Picatinny Anodized