New and high quality. Professional guitar and bass tuner With volume, bass, middle, treble, pres control knobs. LCD display, easy to read. Low battery check LED. Auto and manual tuning mode. Powered by 6F22 9V battery (No Battery) Principle: Pick up the vibration of through the piezoelectric strip, drive it with , input it to the host computer, amplify the signal through the host circuit board, and output it to the speaker. This pickup is an active pickup. 1. Frequency Response: 20Hz-20KHz 2. Control Range: Bass: +/- 12dB at 60Hz Middle: +/- 12dB at 500Hz Middle 2: +/- 12dB at 1.2KHz Treble: +/- 12dB at 3KHz Presence: +/- 12dB at 8KHz Mid2. Control: 600Hz-2KHz 3. Tuning note: Chromatic/Guitar Mode 4. Chromatic & Guitar Tuning Mode(7B/6E/5A/4D/3G/2B/1E) 5. Pick-up: Piezo Ceramic Pick-up Colour:As Shown Material:plastic Size:9.8 x 5.5cm Package Contents: 1 x pickup Kit(The words on the product may vary due to different product batches, but it will not affect the use) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.