Lightweight, aluminum bolt knob features a tapered, oversize design to deliver fast, positive bolt cycling for all types of bolt action rifles. Unique, stepped and grooved exterior adds muscle memory to aid your reflexes in learning to grasp and operate the bolt handle the same way every time for more consistent shooting form. Hollowed recess on bottom of bolt handle reduces weight even further for a light bolt lift and easy cycling. Installation requires machining and threading of bolt handle. Mfg: Brownells SPECS: Aluminum, matte black, anodized finish. 1.6" (4cm) long, O.D. tapers 1.1" (2.8cm) to .40" (1cm). 1 oz. (28g) weight. 5⁄16" - 24 tpi. Includes instructions.