Stainless steel SS Hex bolts as per DIN 931 , 933 , 912 in stainless steel grades SS 304, SS 316, SS 316 L and A2-70, A2-80 and A4-70 and A4-80, 316S31 grade for water projects and water pipelines http://www.roll-fast.com/stainless-steel-bolt.htm