... (while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs &6+ ) plated,anodic oxidation,etc Dip plating black ... ,etc Polishing Grinding and polishing,etc,except mirror finish (3),Ability for the tolerance Roundess0.002mmCylindricity0.003mmRoughnessRa0.32Straightness0.01/200mm ... industry is machined hardware fastener ,especially the cutting/turning parts. Grade 5 hex king bolt