It's a buffer similar to the Vitalizer WV VZW-1 but made for low-tuned instruments. By placing it on the closest spot from guitar/bass in the signal chain, the Vitalizer BF tightens the bottom end that is tend to be blurred with bass, 7/8 string guitar, and drop tuned guitar. Also, it will help prevent degrading the signal or tonal change and reduces the noise from different environmental situations when the pedal is placed in the beginning of the signal chain of the pedalboard.