First of all a few personal words: this analog overdrive-pedal is one of the best around, and certainly the best in its price-range. At least from my point of view (hearing) - and it can keep up with quite more expensive pedals. It's ideal for bluesy- and crunchy Rock-sounds and for that little bit extra for soloing. The character of the guitar will still be obtained.
With the drive-control the overdrive level can be adjusted infinitely variable from nearly clean to maximum Overdrive. Further controls are Level and Spectrum (this enables warm midths from 0-5 and for more treble and bass from 5-10).