Multifunctional outboard preamp with sound quality adjustment. - Brand: bartolini - Model Name: NTBT - Function: Outboard preamp - Controls: Gain, Treble, Bass, Volume, Tone Boost - Accessories: Box, instruction manual, rubber feet, 9V battery This is an outboard preamp based on the active circuit used in Larry Graham's bass. This is just my personal impression, but using this preamp does indeed give a sense of Larry Graham's sound. I am selling it because it no longer suits my current playing style.