hex bolt 1.Surface:black,phosphated,galvanized.. 2.Grade:4.8,8. ... .9 3:Material:mild steel,45# steel,40Cr,42CrMo high strength hex bolt, hex cap bolt, balck bolt1. Surface:black oxide, phosphated,galvanized, Dacrotized2 ... quality control(3) very reasonable and competitive price China fastener high strength hex bolt