This is the same passive tone control that we use in our guitars but shifted down an octave to accommodate bass guitar frequencies. It's similar to the Gibson Varitone switch in function. We use a quality 6-position switch that features five frequency settings in addition to bypass. Our design is vintage correct and a true notch filter. A "two wire" Varitone is not a proper notch filter. See the picture above for the frequency response. The Pentatone switch comes pre-assembled and ready to install--just connect the input and signal and ground output wires. Includes chicken-head knob, our 6 position black dial plate and the switch.