Features: Full metal shell, durable and exquisite. A4 for pitch button. Flat for flat button. Screen shows note name, tuning meter and calibration, pitch and flats. Output jack: 1/4" mono audio jack for signal output. Input jack: 1/4" mono audio jack for connecting guitar. True bypass footswitch design. How to Use 1. Connect a DC 9V power into the pedal. 2. Link the input, and turn on the tuner by pressing on ON/OFF button. 3. If you want to change the pitch, then press A4 button. The pitch ranges from 430Hz to 450Hz.