... ~16.0mm Standards: ASTM, BS, DIN, GB, JIS used mattress spring tempered spring steel wire Grade:55CrSi,60Si2Mn,65Mn ... 0mmStandards: ASTM, BS, DIN, GB, JISAdvantage:1. Marerial: we select good quality spring steel wire rod.2. Surface treatment: advanced ... could improve the fatigue life of spring5. Applicable Industriesl: Widely used in automobile, elevator, motorcycle, electric switches, high-speed rail, ...