GMT M90 Spring

This is a M90 spring made by GMT. It should do about 330 fps but this could be way off depending on your gun. This is a dual stage spring, which means the coils get farther and close together in different parts of the spring. This is the way all aftermarket springs are while stock springs are constant rate. It changes how much force the spring applies at different points in the stroke. The low velocity of this spring makes it best for high rate of fire setups for CQB or other close range areas.

Features:
- About 330 FPS
- .0525" (1.32mm) wire diameter
- Best for high speed CQB setups

UASR rating: 2.69DR
Spring rate (6kg test): 552N/m
Spring length: 176mm
More information on UASR ratings here and here.