hex bolt 1.Surface:black,phosphated,galvanized.. 2.Grade:4.8,8.8,10.9,12.9 3:Material:mild steel,45# steel,40Cr,42CrMo ... , balck bolt1. Surface:black oxide, phosphated,galvanized, Dacrotized2. Grade:4.8, 8.8, 10.9, 12.93. Material: mild steel, 45# steel, 40Cr ...