This A/B pedal has a high quality buffer circuit that combines two classic buffers into one, the warm transistor based "Tube Screamer" type buffer and the clean and transparent "Klon" type buffer to create one completely transparent, unity gain buffer that's warm, natural sounding, and feeling. Perfect for getting that tone sucking tuner out of your signal chain. This circuit does not operate with a battery. Using a dedicated power supply, it can be powered by 9, 12, or 18 volts to create varying degrees of headroom.