... .Grade:4.8,8.8,10.9,12.9 3:Material:mild steel,45# steel,40Cr,42CrMo high strength hex bolt, hex cap ... bolt, balck bolt1. Surface:black oxide, phosphated,galvanized, Dacrotized2. Grade:4.8, 8.8, 10.9 ... quality control(3) very reasonable and competitive price China fastener high strength hex bolt