Artec VTB2 Vintage Tone Controller Active Circuit
Here we have the Artec VTB2 Vintage Tone Controller.
If you want a smaller version of the VTC Unit with more gain options, this is ideal.
It has two switches that let you choose between three different levels of gain: True Bypass (no effect), Overdrive Boost (a bit of crunch), and High Gain (a lot of distortion).
You can use it with any kind of pickup in your Guitar or Bass. This runs on a 9v battery.