FISHMAN MODEL B bass preamp with treble, bass, and volume adjustment knobs. - Brand: FISHMAN - Model: MODEL B - Type: BASS PRE-AMP - Connections: AMP, INSTRUMENT - Adjustment Knobs: TREBLE, BASS, VOLUME Thank you for viewing. I used this with an Underwood pickup on my double bass. It was convenient for quickly adjusting the volume and tone, especially when switching between pizzicato and bowing, as it can be clipped to a belt. Although it's an older product, it's in beautiful condition with no scratches. (Please note that this is a used item.) I am selling it as I am parting with my instrument.