Descriptions: These T slot nuts are made of 45 steel, black oxide finish, features high hardness, high strength, durable in use. It is used for T-slot aluminum extrusions to connect other parts. And T-Slot nuts enable the user to add clamps to a fixture without tearing down existing clamps. Features: Made of 45 steel, black oxide finish, features high hardness, high strength, durable in use. Undersized to fit machine table slot case hardened.It is used for T-slot aluminum extrusions to connect other parts. T-Slot nuts enable the user to add clamps to a fixture without tearing down existing clamps. Specifications: Material: 45 steel Surface treatment: black oxide Thread: M8Size: as the picture Weight: 100g,138g Package Included: 5 x T Slot Nuts .