Neewer Guitar Plug Amp Digital Delay Effect Rechargeable Electric Guitar Headphone Amplifier, Portable and Compact, NW-GA-5 Digital delay effect electric guitar plug headphone amplifier, powered by built-in rechargeable lithium battery Designed with 3 knobs: Echo,F.back, Time 6.35mm/0.25in plug, just plug into guitar jack, no need of installation Uses the headphone jack to connect headphones, portable speakers, mixer or recorder Note: Guitar and headphone are NOT included