The Mooer Trelicopter Tremolo effects pedal offers classic tremolo effects with a huge range of speeds and depths. You can even tweak the color of the sound with the BIAS knob. Its full metal casing makes it durable and road ready, and like most great effClassic optical tremolo with huge range of speeds and depths. BIAS knob brings various color of the tremolo sound. Full metal shell - Pedalboard friendly - True bypass.