Double grooved Spring steel flat bar 1. Spring steel bar 2.Material: 65Mn, 60Si2Mn, SUP9, SUP7, 50CrVA 3. Size: 6*40~20*150 Double grooved Spring ... steel flat bar We're a big steel mill, and ... .Double grooved Spring steel flat bar 1. Material: 65Mn, 60Si2Mn, SUP9, SUP7, 50CrVA etc2.Thickness: 6~20mm, Width: 40~150mm, Length: 2~8m, ...