metric hard lock nut 1,Products DetailesMaterial1.Stainless Steel: SS201, SS303, SS304, SS316, SS410, ... :C36000 ( C26800), C37700 ( HPb59), C38500( HPb58), C27200CuZn37), C28000(CuZn40)4.Bronze: C51000, C52100, C54400, etc5.Iron: 1213, 12L14,12156.Aluminum: Al6061 ...