This is a hopped-up volume pedal with an SHO at it's heart, providing boost, and a copper probe-plate like a Fuzz Probe. As your foot gets closer the volume goes up, but unlike a conventional volume pedal there's no moving parts so you can create instant swells and tremolo effects by tapping your foot on the pedal in time with the band.
The Tremolo Probe is a kind of cross between a theremin volume control and a Super Hard-On. There is a 3-5/8" square copper plate mounted on a chunk of 3/8" clear acrylic that passes over the top of the pedal housing, angles down to sharp turn, and goes back to the pedal. Under the whole mess is a 3 5/8" by 7" sheet of aluminum that provides shielding from annoying ground effects and wires under the stage.
At the he heart of this pedal is a super hard-on circuit combined with a probe controller circuit that I developed for use with the fuzz probe and some other devices not yet released. You can tap on this pedal with your foot to make lovely tremolo sounds that are in perfect time with your foot's movement... so they can be perfectly in time with your performance or the band's tempo changes. You can also use the pedal to make reverse-sounding volume swells or pedal-steel type volume effects.
Here is more info on the Tremolo Probe