Housed in the same size enclosure as any other Chase Bliss Pedal, the Expression Roller allows you to utilize two expression pedal outs from any pedal that has them. They've thought of everything with this one...It's super easy to get used to (and motion actually feels better than a standard expression pedal). It's also built like a tank and allows you to change the polarity of either output. Where has this been all my life?!