The drive dosen't do anything until you put it past 12 o'clock, then it starts to overdrive. Sustain controls the rate of the reverb.
Tone is self-explainatory.
If you turn the drive all the way up and turn the sustain all the way down, you have a overdrive pedal. 10 mine was pretty well beaten up when I got it, and it works fine. It uses 2 nine volt batteries, or a 12-volt adapter. I Need to Get Control. Inc. All rights reserved.