BOLT ,SIZE FROM M6-M72 M100 1 Material:C15,C15E,SUS304 2 heat treated:quenched,tempered 3 finish:SC&EG&HDG Bolt M721 Material:C15,C15E,SUS304 2 heat treated:quenched,tempered 3 finish:SC&EG&HDG 4 ISO9000:2000 certificate bolt (DIN580)1.material:C15,C15E,SUS304/3162.process:hot forging 3.heat treated:quenched,tempered4.finish:SC&EG&HDG M6-M72 Bolt