The Aguilar OBP-2 was designed to give bassists fat tone while being small enough to fit in tight spaces. Wired up with one 9V battery, it will fit into just about any instrument. With +/-18dB of boost and cut at 40Hz and +/- 16dB of treble boost and cut at 6.5kHz you can emphasize the frequencies you want to make your bass sound great in any mix. Add a second 9V for an extra 6dB boost.