bolt Technical information The size under M20 are cold forged, the size on the M22 above are hot forged, the nuts are the same. The grade of the hex bolts(Metric) are Grade 4.8, 5.8, 6.8, 8.8, 10.9, 12.9, ; (ANSI)Grade 2, 5, 8, B7;the grade of hex nus(Metric) are grade 6 S181, 8 ,10, (ANSI) Grade 2, 5, 8 ,and so on. The material we use carbon steel: C1008, C1010, C1035, C1045, alloy steel 40Cr, 35CrMo 42CrMo ,and so on. And some stainless steel A2,A4, SS304, SS306 and so on. We have two pieces” made in Taiwan” heat treatment equipments We have two packing items, one is carbon bulk, another one is small box. We can make the surface are : plain, black, white blue zinc plated, white zinc plated, yellow zinc palted, hot dip galvanised and so on.