Metric Thread DIN912 M3 Black Grade 12.9 Alloy Steel Hex Socket Head Cap Screw Bolts M3*(3/4/5/6/7/8/9/10/12/14/15~50) mm metric thread din912 m3 black grade 12 9 alloy steel hex socket head cap screw bolts m3 3 4 5 6 7 8 9 10 12 14 15 50 mm