NOTE: I originally gave this 5 stars, but after 2-3 years of light use, it started randomly feeding back when I would engage it with the footswitch.
Note: This is not an overdrive or distortion pedal. It is a fuzz pedal! Different beast.
Unlike passive bass and guitar tone controls, the tone control increases high end when turned up. The "bass boost" switch selection adds bottom end back in; this can provide the bass version of scooped mids, or just put some bottom end back on your fuzzy slap.
The "dry" position on the switch mixes a set amount of your dry signal with the distorted output, which lets you tame the fuzz somewhat.
If you want a fuzz for your bass, if you like the sound of a Big Muff Pi for guitar, this is a great deal for your bass.