T-slot nut is used for T-slot aluminum extrusions to connect other parts Undersized to fit hardened machine case M12 T-slot nuts made of 45 steel, black oxide finish, features high hardness, high strength, durable in use The bottom of the T-slot nut is staked to prevent protrusion from protruding T-slot nuts allow user to add clamps to a device without tearing out existing clamps