Anarchy Outdoors Bolt Knob Big Bertha Black. This bolt knob allows our hulk shooters to grasp their bolt handle and move it with ease. The hourglass shape of this bolt knob increases dexterity for the shooter and the diamond-shaped rivets increase grip. Those that like this design but prefer a smaller bolt handle should check out Little Bertha Bolt Knob. Specifications for Anarchy Outdoors Bolt Knob Big Bertha: Manufacturer: Anarchy Outdoors Threads per Inch: 5/16x24 Length: 1.753 in Diameter: 0.945 in Features of Anarchy Outdoors Bolt Knob Big Bertha The design allows for easy handling; Included rivets allow for better grip; Compatible with all custom Anarchy Outdoors handle products; Standard thread knobs will fit on the Christensen Arms Standard Rifles Package Contents: Anarchy Outdoors Bolt Knob Big Bertha Anarchy Outdoors 791617485662: Bolt Knob Big Bertha Black