Area 419 Finger Groove Bolt Knob For Defiance Actions Stainless Steel Black Nitride. Its main feature is the finger groove which allows you to manipulate the bolt with just your pointer finger without searching for the ideal position each time. Your finger automatically catches in the groove to assure the fastest smoothest bolt manipulation. There are two knurled surfaces located on either side of the groove to give a sure grip.made in specialized factories from 6061-T6 aluminum and anodized flat black.Defiance and Remington bolt knobs are threaded 5/16''-24.Remington knobs are 1-5/8'' long to accommodate shorter bolt handlesBergara and CZ 457 bolt knobs are threaded M6x1 and also work on many Accuracy International rifles.Mausingfield bolt knobs are internally threaded 10-32. Will only work on Mausingfield and Nucleus Bolts Specifications for Area 419 Finger Groove Bolt Knob For Defiance Actions: Manufacturer: Area 419 Fabric/Material: 6061-T6 Aluminum Condition: New Country of Origin: USA Weight: 0.2 lb Quantity: 1 Package Contents: Area 419 Finger Groove Bolt Knob For Defiance Actions Area 419 419-KNOB-DEFSSBN: Finger Groove Bolt Knob For Defiance Actions Stainless Steel Black Nitride