The Mooer MEP-TC Trelicopter Optical Tremolo micro effect pedal packs an incredibly BIG sound into a very small package. Our Trelicopter is a classic optical tremolo with huge range of speeds and depths. The Bias knob brings out various colors of the tremolo effect. Turn it up to crack down on the signal, turn it up to loosen it. The Mooer Trelicopter emulates the classic tones of the Demeiter Tremulator. The pedal switching is true Bypass, so the sonic integrity of your instrument is never lost. Rugged ?Full metal Casing and quality switching in a small and exquisite design.? Dimensions (HxWxD) 03.5 X 42 X 52 mm Requires a 9 Volt Centre Negative power supply for operation (not supplied). Suggested model Crossfire CAP-1