The Boss PQ-4 Parametric Equalizer brings together a unique arrangement of Boss features like sweepable mid and high frequencies with matching level control, an autonomous low control with present and 18dB cut or boost, and an overall level control with the same 18dB cut or boost. One of the shorter-lived Boss pedals of the '90s because some users didn't care for the interface, this versatile equalizer is one of the effect giant's sleeper hits that some guitarists will immediately take to.