The Joyo Tremolo JF-09 is an optical circuit tremolo like in the old Fender amplifiers used. All analog, with gradual smooth oscillation. No need to buy a pricey pedal, this baby will do the job well when you need that subtle wave for ambiance. Speed can go from a barely noticeable pulsing all the way to a fast choppy stutter. A nifty feature is the LED light blinks at the rate of the current tremolo speed so makes adjustments easy and intuitive. Specifications This is the tremolo of the beloved classic tube amplifiers--using the same photoelectric tube circuitry as the trem in those amps of old. Intensity and Rate knobs make it easy to adjust the tone and vibe. True bypass design minimizes tone loss. Aluminum alloy casing with stoving varnish finish.