The DigiTech Brian May Red Special Pedal essentially gives you all of Brian May's signature tones in one unit. It features Gain, Level, Treble, Bass, Control, Guitar, and Model knobs, enabling you to dial in exactly the tone you want.

The Gain knob adjusts the amount of distortion. 

The Level controls the output level.

Treble and Bass are pretty self-explanatory, adjusting the high and low frequencies in the sound.

The Control knob acts serves different functions depending on the Model selected. It controls the amount of effect on settings like "Keep Yourself Alive" and the rate of the effect on "We Will Rock You". It also adjusts the tone on "Tie Your Mother Down". On the "Brighton Rock" setting, the Control knob adjusts the frequency of the delay.

The Guitar knob lets you select three basic options depending on the guitar you have. This pedal is designed to make single-coil Strat-style guitars and humbucker Les Paul-style guitars sound like a Red Special. So, selecting the "SC" mode makes your Strat sound like Brian's guitar while the "HB" mode makes any guitar with humbuckers sound like a Red Special. This button also has a Red Special mode. If you have a Red Special style guitar, this mode will make the pedal work to suite your guitar.

The Model knob lets you select from 7 different classic Queen tones. These tones are:

1. "Keep Yourself Alive"  Rich tape-flange intro on toe mode and solo with tape flange on heel mode
2. "Bohemian Rhapsody"  Classic vocal-like solo tone with loads of sustain on toe mode and Rhythm and Finale Orchestral Fanfare with the legendary "Deacy" amp on heel mode
3. "Tie Your Mother Down"  Intro with sustain and distortion on toe and solo close-miked with higher gain for more sustain and distortion on heel mode
4. "We Will Rock You/Champions"  Creamy distortion with a churning phaser effect
5. "Crazy Little Thing Called Love"  Acoustic guitar model with slight delay on toe and clean rockabilly Telecaster tone with reverb
6. "Brighton Rock Solo -Live"  Solo with 3 amplifier delay and tight chorus on toe and 3-part Orchestral Harmonizer effect on heel
7. "Deacy Tone/A Winter's Tale"  Raw tone through Brian's "Deacy" amp and delay and reverb added as a post effect for mystic sounding solo

The Crybaby style design of this pedal adds to it's versatility, giving you the ability to adjust effects on certain models as you are playing. For example, on the "Brighton Rock" setting, rocking the pedal forward increases the strength of the delays, while rocking it back decreases it.

This pedal is something no true Queen fan should be without, as it gives you all of Brian May's best and most recognizable tones without the hassle of buying three vintage AC30s, a replica of Brian's guitar, a super pricey treble booster, and a train-load of effects pedals.