S150 / SP150+ Modify progressive coil spring

S150 / SP150+ Modify progressive coil spring

Progressive coil steel spring designed to be fitted to any electric airsoft gun (including those with manual tension, if compatible with AEG springs) having a Tokyo Marui standard gearbox.

The progressive winding of the spring makes it easier to tension the spring and reduces the load on the system, while maintaining the full power of the spring.