Pedal Features:        Full metal shell, durable and exquisite.      3 controlling knobs and 1 switch are accurate and high sensitive.      Oct1 knob: Adjust the volume of the first voice of octave.      Oct2 knob: Adjust the volume of the second voice of octave.      Dry knob: Adjust the volume of dry signal.      Mode switch: Switch between top(+1 OCT and +2 OCT), both(-1 OCT and +1 OCT) and bottom(-1 OCT and -2 OCT) mode.      Output jack: 1/4'' mono audio jack for signal output.      Input jack: 1/4'' mono audio jack for connecting guitar.      True bypass footswitch and lever designed to prevent stamping on operation knobs.       Specifications:        Model: AROMA AOS-3      Effect: Polyphonic Octave      Material: Aluminium Alloy      Input Impedance: 470K Ohms      Output Impedance: 100 Ohms      Current Draw: 68 mA       Power supply: AC Adapter 9V DC (not included)      Item Size: 9 * 3.8 * 4.8cm / 3.5 * 1.5 * 1.8in      Item Weight: 151g / 5.3oz      Package Size: 12 * 7 * 6.5cm / 4.7 * 2.7 * 2.5in      Package Weight: 246g / 8.6oz         Note:      Please use the 9V power adapter whose polarity is positive pole outside and negative pole inside. Otherwise, the product may not work properly.         Package List:      1 * Guitar Effect Pedal      2 * Adhesive Tape      1 * User Manual (English & Chinese)      1 * Hardcover Box