Alexander Pedals Litho Boost Volume - Controls the output volume of the boost. Crank it to overdrive your tube amp. Contour - Set low for transparent and glassy boost. Or set it higher for fat and juicy boost. Your call. Tone - Adjusts the high frequency content of the boosted signal. The "neutral" setting is around 2 o'clock. The Litho Boost requires a 9V DC power supply with a 2.1mm pin, center negative Does not use a battery