GOST R 52644 - 2006 高强度六角头螺栓 Hexagon Bolts for High-Strength Structural Bolting with Large Width Across Flats - Product Grade C - Property Classes 8.8 and 10.9
GOST R 52645 - 2006 钢结构用高强度六角螺母 Hexagon Nuts for High-Strength Structural Bolting with Large Width Across Flats - Product Grade B - Property Classes 8 and 10