nux gp-1 guitar headphone amp (battery inside) nux gp1 is a portable guitar plug amplifier with distortion sound. you can play your electric guitar anytime, anywhere. plug your headphones and enjoy your gp1 with a british rock distortion. also you can adjust the gain and tone level for different tastes. <br><br>features: <br>compact and light-weight design, easy to carry. <br>built-in distortion effect. <br>designed with 3 adjuster: level, tone, gain. <br>0.25in plug, just plug into guitar jack, no need of installation. <br>powered by two aaa 1.5 alkaline batteries