1.4mm Spring 2.Material: 45#,60#,65#,C70DA,C82DA,70#,80#,72A,72B,82B. 3. ... 4mm Spring Of Grade 452. Material: Steel GradeGB StandardCarbon%Silicon%Manganese%Phosphorus%Sulphur %Chromium%Nickel%Cuprum%45#0.44-0 ... mattress spring steel wires.6. Our other material: 60#,65#,C70DA,C82DA,70#,80#,72A,72B,82B.7. Wire Gauge ... Spring Products 4mm Spring Of Grade 45(45#,60#,65#,C70DA,C82DA,70#,80#,72A,72B,82B)