JARD Action Knob Rifle Bolt Tear Drop 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 Action Knob Rifle Bolt: Manufacturer: JARD Color: Black Features of JARD Action Knob Rifle Bolt: Color: Black Model: Tear Drop Material: Aluminum Outer Diameter: 0.850" Length: 1.450" Thread Pitch: 5/16x25 Package Contents: JARD Action Knob Rifle Bolt JARD 4111: Action Knob Rifle Bolt Tear Drop Black