... steel and so onSizeM6-M42 LengthM16-300Type of headSquare,Hex,Flange,Hex socket,T-Head and other you can chooseSurface treatmentBlack ... accroding to your drawing or your sampleRegarding to Nuts Type of NutSquare,Hex,Flange,Hex socket,T-type,Coupling,wheel ,acorn,tapper ... ) We have 10years experience of manufacturing fasteners DIN6914/6915 Hex Nuts M12-M33 Bolt and Nut