Product name:T-shape screw nut accessories Size: 0.42inch Colour: Black T-nut metric cam screw replacement kit, compatible with standard rail systems, with threaded locking screws, and nuts. Supplied with two T-nuts and two different lengths of capped button screws to ensure compatibility with a variety of handguard or front end thicknesses. Made from high quality hard anodised aluminium with a beautiful black oxide finish for rust and slip resistance. Reusable self-locking threaded patches have been added to the screws to ensure a secure fit during installation.