... fastener field 1,Name: Black thread bolt;Thread bolt;Black bolt 2,For the similar bolt,what ... can we do ?(1), Ability for the ... + ) plated,anodic oxidation,etc Dip plating black oxide coating,hot dip galvanizing,etc Flame plating ... polishing,etc,except mirror finish (3),Ability for the tolerance Roundess0.002mmCylindricity0.003mmRoughnessRa0.32Straightness0.01 ...