Spring coil
FIG. 1 is a front view of the spring coil, the rear  view of which is identical with the front view; 
     FIG. 2 is a side view of the spring coil, the opposite  side of which is identical; 
     FIG. 3 is a top plan view of the spring coil; and 
     FIG. 4 is a bottom plan view of the spring coil.