YueYueZou&reg; Acoustic Guitar Preamp 5 Band EQ Equalizer Piezo Pickup Tuner LCD With this preamp, you spend less time tweaking controls and more time playing. 4-band equalizer, push bass/middle/treble to adjust volume frequency. Phrase and volume control. LED for battery check, replace battery when Batt lights. Powered by a 9V battery (not included).