In the words of JHS Pedals:

The JHS Pedals Colour Box began with a simple idea: create a pedal that sounds like plugging directly into a vintage preamp and cranking it. No amp, no speaker, just DI goodness. Well, the Colour Box became much more as we got into designing it. Thus we decided it was time to pare it down and give guitar players and bass players a simplified version that gives you the distinct compressed overdrive and fuzz sounds youve heard on so many classic recordings. The Crayon is just that, a powerful little box that has all the color and characteristics of a vintage studio preamp when cranked.