It is used for T-slot aluminum extrusions to connect other parts. Spec: Features: Made of 45 steel, black oxide finish, features high hardness, high strength, sturdy in use. 45 Steel T Slot Nuts,5 Pcs Black Oxide Finish T Slot Nuts M12 Threads Fit Into T-Slots In Machine Tool Tables,High Hardness, High Strength, In Use T Slot Nuts 5 Pcs Black Oxide Finish M8/10 Threads T Sliding Nut Fasteners Fit Into Aluminum Extrusion Nuts Bottom of T-Slot nut is staked to prevent the stud from protrusion. Specifications: Material: 45 steel treatment: black oxide Thread: Size: as the picture Weight: 235g Package Included: 5 x T Slot Nuts [High Strength Material] Made of 45 steel with black oxide finish, ensuring durability and long-lasting use. T-Slot nuts enable the user to add clamps to a fixture without tearing down existing clamps. Buy Black Oxide T-Slot Nut, Grade 5, Pack of 5 at Ubuy Undersized to fit machine table slot hardened.