... two head threaded stud bolts1) Material: High quality carbon steel Class :4.8, 5.8, 6.8, GR.2, A307 2) Material ... :Alloy steel :20MnTiB ,40Cr ,42CrMo Class :8.8, 10.9,12.9 ,GR.2,GR.5 ... :stainless steel :302 ,304 ,305 ,316, 304L ,316L ,410, 430 Class: A2-50 ,A4-50 , A2-70 ,A4-70 ,GR.B8 ...