Boss OS-2 Warp "Theremin" photo-eye, phasing distortion, treble-boost Makes your Boss OS-2 into a dynamic fuzz machine with envelope filtering, phase, lower octave, and foot controllable "theremin" madness. The four added functions are : "Theremin" Photo Eye Envelope Filter Dynamic Phaser Filter Treble Boost With all modes off the pedal acts as it normally would. There is a bit of bleed through while bypassed if you have all your setting maxed and various combinations of modes on.