... Material: 40Cr Grade: 10.9 or 12.9 Rear wheel hub bolt 1.Surface:black,phosphated,galvanized.. 2.Grade:4.8 ... :mild steel,45# steel,40Cr,42CrMohigh strength hub bolt, hub bolt and nut, high strenght bolts 10.91. Surface:black,phosphated,galvanized, Dacrotized2 ... quality control;(3) very reasonable and competitive price. Rear wheel hub bolt