Black steel hinge pin Surface:BO Process:Machined and turned SGS ... field 1,Name: Black steel hinge pin;Steel hinge pin;Black hinge pin 2,For the similar hinge pin,what can we do ... ?(1), Ability for the material of this kind of hinge pin: Grade3.6,4.6,4.8,5.6,6 ... the surface finish: ElectroplateZinc plated(while,colour,dacroment),Nickel plated,copper plated,gold plated,chrome(3+Rohs &6+ ) plated,anodic ...