One of the classic guitar effects of all time. The pedal creates a vocal like sound by sweeping through the frequency range of your guitar. Most commonly controlled with the foot allowing you to work in real time and sequence the effect to what you are playing. Some pedals over an auto function allowing you to switch on and off a preset wah effect. Here you will also find envelope filters. This pedal reacts to how hard you play, play hard and you get a treble boost and as the signal drops the boost dies away, the ultimate funk tool.