Rocket Airsoft M140 AEG Spring

Rocket Airsoft M140 AEG Spring. Silver type upgrade spring that is non-linear. Fits in all gearboxes. A higher FPS than standard for heavy duty upgrades. FPS will be 450, maybe around 460 or so. (please note: packaging may be generic or labeled as 'Rocket Airsoft', but is made by SHS OEM). Not recommended unless you're an experienced tech.