Black steel hinge pin Surface:BO Process:Machined and turned SGS audited More ... 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 ... .P.S:For us,the most competitive industry is machined hardware fastener ,especially the cutting/turning parts. Black steel ...