This is a vintage 1975 MXR Phase 100 phaser pedal. Since the early seventies, MXR phasers have always been regarded as the most classic of analog phaser pedals and have been used by greats like Jimmy Page and Eddie Van Halen. This particular example is in near perfect cosmetic shape and perfect working condition. From the slowly shifting tonality at one extreme to the fast bubbling at the other, this is organic phasing that seems to embrace the sound of the guitar rather than something simply slapped on top of it. It can nicely replicate simple UniVibe sounds rather easily, and is actually quite versatile for a one-knob effects pedal.