Tier One Tactical Bolt Knob Black One Size. Made from Aluminium 7075T6 and Hard-coat Anodised for maximum durability. Please Note: Some gunsmithing may be required to facilitate fitting to some rifles. This product come with their lifetime warranty on parts and defects and their 30 day return policy for peace of mind. Specifications for Tier One Tactical Bolt Knob: Manufacturer: Tier One Fabric/Material: Aluminum Color: Black Package Contents: Tier One Tactical Bolt Knob Nil Tier One T1TACBK: Tactical Bolt Knob Black One Size