It has three knobs: Volume, Tone, and Fuzz. It also has an additional Deep Switch, which provides crushing low-end boost. The on/off footswitch is true bypass, but even when it is on, this pedal is able to preserve a full tone on most settings.
All MXR 3 Models
This pedal is awesome for getting that gritty bass tone for metal/rock.
The sound is so easy to get what you want out of it, 2 knobs make it simple to get that tone you want without all the annoying mucking about with 100 frickin' knobs that you don't know what the hell they all do.