class 12.9 Inside hex carbon bolts 1.high quality 2.favorable price ... screwmaterialCarbon steel, stainless steel grade4.8/8.8/9.8/10.9/12.9 sizeM5-M6Surfaceplain,zinc plated,black oxide,hot dip galv ... know more,pls feel free to contact us. class 12.9 Inside hex carbon bolts