From the manufacturer:
Precision Armament TBK-6 Tactical Bolt Knob is fully machined from light-weight high strength 7075-T6 aluminum bar. This oversize tactical bolt knob features high quality Sure-Grip CNC engraved texturing. Sure-Grip™ provides a dependable non-slip surface for fast, reliable cycling without being sharp or abrasive like knurling. Features standard 5/16-24 threads for Remington 700 and similar size bolt handles. Mil-A-8625 hardcoat anodized, matte black finish.
Installs easily on 5/16-24 pre-threaded bolt handles; requires gunsmithing for non-threaded bolt handles.
An enlarged bolt knob does more than add leverage for lifting a bolt handle. It adds space between the bolt handle and the stock of your rifle allowing easier hand positioning for lifting the bolt. The larger knob works in the hand smoother as well--bare hands or gloved. Precision Armament also incorporates a minor texture on the knob that aids bolt manipulation in wet environments.
Email us HERE about gunsmithing services for bolt handle threading.