You are bidding on a Zvex Tremolo Probe. This is one of those effects that people are amazed when they watch you use it. The tremolo (or volume) is controlled by a RF frequency through the copper plate. The closer your foot (or anything else) gets to the copper plate, the louder the volume gets. You can do tremolo in time with the rest of the band, you can do volume swells, you can even set it to be a boost. I mainly used this as a volume pedal and it sounded great. You can control the level of volume by the volume control on the end of the unit. Please see below for the description from the Zvex website. International bidders please contact me for shipping quote prior to bidding. Also, check out my other auctions for more boutique effects. Thank you for looking and happy bidding. 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. It also serves to protect the knob from being knocked off if you drop it on that end... and it makes a nice toe chopper if you are barefoot, so (legal disclaimer:) DO NOT DROP THIS PEDAL ON YOUR FOOT! IT IS HEAVY AND HAS VERY POINTY CORNERS THAT COULD DAMAGE LIVING CREATURES AND FINE HARDWOOD FLOORING. ALSO, YOU COULD BREAK SOMETHING. Like your dog. What does this pedal do? How does it work? 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. The copper antenna projects a field of RF energy that is affected by your foot (or other appendage), altering the circuit that generates it, an in so doing, increasing the brightness of that LED on the top of the pedal and also controlling the master volume of the output. You can set the drive of the pedal with the knob on the back... it gets pretty darn loud, so watch out. It will distort in an interesting way when it is cranked. Basically, the reason it is called the tremolo probe is that you can tap on the antenna at any speed and your sound will be a nice tremolo in time with the band. It is possible to set the volume to be up slightly when your foot is off the antenna and come up louder as your foot approaches the antenna... see next.