... special fastener Name: hex nut with internal thread and castle screw Ability for the material of this kind ... the surface finish: ElectroplateZinc plated(while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs &6+ ) plated ... Flame plating Light oil,spray coating,electrophoretic coating,etc Polishing Grinding and polishing,etc,except mirror finishAbility for the tolerance: Roundess0 ...