JARD Bolt Action Knob Round Knurled Outer Diameter 0.850in Length 0.925in 5/16x24 Aluminum Black. All our knobs feature 5/16-24 thread pitch - The industry standard. All of our knobs are machined aircraft grade billet aluminum for a lightweight feel and anodized for a clean polished finish. Specifications for JARD Bolt Action Knob: Manufacturer: JARD Fabric/Material: Aluminum Color: Black Package Contents: JARD Bolt Action Knob JARD 4077: Bolt Action Knob Round Knurled Outer Diameter 0.850in Length 0.925in 5/16x24 Aluminum Black