A torsion spring is a spring that works by twisting its end along its axis; that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a torque in the opposite direction, proportional to the amount (angle) it is twisted. 

Inner Dia: 2.5mm

Outer Dia: 4mm

Length of Spring: 4mm

Length of arms: 9mm

Arms relative position: 180 Degree

Hardness: less then medium size one (Medium hard)

Package Includes:

1 X Torsion Spring Small Size(5pc set)