Andoer Acoustic 5-Band EQ Equalizer Preamp Piezo Guitar Tuner for Guitar Player With this preamp, you spend less time tweaking controls and more time playing. Tone and volume control. With volume, bass, middle, treble, pres control knobs. LCD display, easy to read. Powered by 6F22 9V battery (not included). Low battery check LED. Auto and manual tuning mode.