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