Precision Armament TBK Tactical Bolt Knobs are fully machined from light-weight high strength 7075-T6 aluminum bar. These tactical bolt knobs 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.TBK-6 Oversize Tactical Bolt Knob fits easily on 5/16-24 pre-threaded bolt handles; requires gunsmithing for non-threaded bolt handles.