Guitar pedal effect - overdrive. The Drive – Bi is a dual channel, op-amp gain circuit. Designed to cover medium to high level amp style drive that is extremely dynamic and raw. Low channel adds grit, sustain, and overdrive to your amp while still pushing output. Hi gain mode expands low end, saturation, and output compression for huge warm tones. This is one of the most natural sounding gain pedals on the market. Great for solo boosts as well. Power supply with 9V battery or an optional 9V DC power supply.