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.