... years experience 1,Name: Steel hex coupling;steel coupling;hex coupling2,For the similar coupling ,what can we do ?(1), ... while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs &6+ ) plated,anodic oxidation,etc Dip ... etc Polishing Grinding and polishing,etc,except mirror finish (3),Ability for the tolerance Roundess0.002mmCylindricity0.003mmRoughnessRa0.32Straightness0.01 ...