The World's Greatest Varitone for Bass Our Varitone can replace a tone knob or work in conjunction with it. The Varitone has enjoyed a resurgence as of late. Passive, No Battery! 100% Dependability, 0% Failure Rate to withstand the rigors of professional musicianship all bassists appreciate! Why is ours the best? Quiet switching, highest quality components, warm tones and musically selected capacitor and inductor values. The Varitone is a 6 position rotary switch that invokes a notch filter mid range cut that starts high and goes down through the frequency spectrum as you advance through the positions for a nice selection of midrange dips. Endorsed by the Grammy Winning bassist and composer Mark Peterson and used on Ben E. King's, Bob James' and Casandra Wilson's latest releases as well as the soundtrack for the award winning film "Free Angela Davis and All Other Political Prisoners." Bassist for Gary Clark uses them, too. Guaranteed great tone!