Active Coils - Those coils which are free to deflect under load.

Ground ends-Ends of springs are ground to provide a flat plane.

Closed ends - Ends of springs where the pitch of the end coils is reduced so that the end coils touch.

Free length - The overall length of a spring in the unloaded position.

Ground ends - Ends of springs are ground to provide a flat plane.

Hole - This is the minimum diameter of the hole in which spring can work.

Load - The force applied to a spring that causes a deflection

Loops - Coil-like wire shapes at the ends of extension springs that provide for attachment and force application.

Mean coil diameter - Outside wire diameter minus one wire diameter.

Pitch - The distance from center to center of the wire in adjacent active coils.

Total number of coils - Number of active coils plus the coils forming the ends.