... 3.surface zp,black,hdg 4stainless steel, steel,etc carriage bolt 1.Size:M2~M42 LTH20-200mmm2.high quality competive ... price.3.material of carriage bolt:stainless steel ,carbon steel,copper or according require4. ... surface treatment of carriage bolt:Passivation,Zinc-Plating black or according to customers' ...