SR25 Retro Arms SiCr spring with a progressive irregular coil M140

M140 Retro Arms SR25 Spring SiCr with a progressive irregular coil

Main spring made of chrome-silicon steel, for Long type gearboxes. The progressive coil makes it easier to stretch the spring without losing power.
Spring dimensions:
Inner: 11.30 mm
Outer: 14.50 mm
Length: 185 mm