Rowin Trelicopter is a Classic optical tremolo with huge range of speeds and depths BIAS knob brings various color of the tremolo effect soundFeatures and Specifications Rowin micro effect pedals pack an incredibly BIG sound into a very small package. Very small and exquisite Features: 1. Power Supply: 9V DC (Negative in the center). 2. Depth Knob: Control the depth of tremolo effect. 3. Bias Knob: Adjust the bias of the optical of tremolo unit. 4. Speed Knob: Adjust the speed of tremolo effect. 5. Input Output Jack: Analogy though 1/4 inch mono audio jack. 6 .LED Light: LED indicator shows the working state. 7. True Bypass: True bypass for zero tone coloration. 8.super solid construction. Working Current: 26mA. Weight: 273g(With box) colour: green Material: Zinc alloy size: 9.5 * 4.5 * 4.8cm Package Contents: 1 * Guitar Effect Pedal 1 * User Manual(English) Note: Power supply not included. Please use a 9V DC power adapter whose polarity is negative centre otherwise, the product may not work properly. Package List: 1 * Effect Pedal 1 * Tuner 1 * User Manual(English Chinese) 1 * Year warranty through our store No Duty to Canada and USA FAST 'N FREE USA Shipping Ships from Canada