The amout of initial tension can be varied and should be determined prior to spring
       production.

       Mandatory data:
       1、Controlling Diameter
       1、Controlling Diameter
       a、outside Diameter,O.D.
       b、Inside Diameter,I.D.           
       2、Wire size,material,and class
       3、Numbers of active coils
       4、Rotating Direction(Left or Right)
       5、Free Length
       6、Loading
       7、Type of end