The Zvex Trem Probe, custom-painted by Lisa McGrath, is a hybrid of a theremin volume control and a Super Hard-On. It features a 3-5/8" square copper plate mounted on a 3/8" clear acrylic chunk that extends over the pedal housing, then angles sharply down and back to the pedal. Beneath this assembly lies a 3 5/8" by 7" aluminum sheet, which shields against unwanted ground effects and stage wires. It also protects the knob from damage if dropped on that end and can be quite sharp if you're not wearing shoes, hence the legal disclaimer.

This pedal's core is a Super Hard-On circuit fused with a probe controller circuit I designed, which is also used in the fuzz probe and other upcoming devices. By tapping the pedal with your foot, you can produce beautiful tremolo effects that sync perfectly with your movements.