The Robotalk is based on the famous Oberheim Voltage controlled filter which was also sold as the Maestro filter sample and hold. It is a cool envelope follower with a 2nd mode. This mode is "sample and hold" and sounds like a synthesizer's sample and hold, similar in sound to the Z.Vex seek wah (actually more like the random mode on the Z.Vex Ooh Wah). The Robotalk is actually THREE effects in one as it has an added LO-PASS filter mode which allows controlling the frequency range with an expression pedal! This makes it into a cool filtery-sounding wah. List price is $280, we are selling them for $252. CLICK HERE for Online Ordering for shipment in the USA for $252 with $5 S & H for one or more.Here is some more information from Prosound's web site, but please return back to my site to order one at my discounted price.