mattress and spring Grade:55CrSi,60Si2Mn,65Mn Dia:6.0~16.0mm Standards: ASTM, BS, DIN, GB, JIS mattress and springGrade:55CrSi,60Si2Mn,65Mn Dia:6 ... .0~16.0mmStandards: ASTM, BS, DIN, GB, JISAdvantage:1. Marerial: we select good quality spring ... ~19103540>6.50~7.001430~15801400~15501500~16501630~17801740~18903540 mattress and spring