Modify - Tokyo Marui A.E.G. Irregular-Pitch Spring - S 120+Modify Tokyo Marui A. E. G. Irregular Pitch Spring S 120+ Finely manufactured from A class piano wire Very durable and strong Irregular pitch coiling for enhanced performance Very Consistent FPS Easy to install Every spring has gone through vigorous and quality tests from the moment a new design leaves the software drawing through to final mass production. Modify Airsoft AEGs coil spring with irregular pitch for the Tokyo Marui is designed for