The OCD pedal is the only pedal that uses 2 x Mosfets configured as "hard clipping to Vref."
The earliest OCDs used 2 x Mosfets plus 1 x Germanium diode, but very quickly these diodes became harder and harder to find, and they became expensive.
Recently I stumbled across a reasonably large stash of the right kind of Germanium diodes so I ponied-up and bought all of them. I then decided to do a small run of the ultimate OCD: a Custom Shop offering with a few circuit tweaks, 2 x Mosfets plus 2 x Germanium diodes, and one hell of a beautiful paint job...
Metallic Teal with a chrome undercoat! This beauty morphs between blues and greens depending on the light and angle. And what would the ultimate OCD be without a Blue LED? The sound?
Great definition, more tube-like feel, a bit wider dynamic range, more sustain, and a more focused single-note tone. And as with all Fulltone pedals... 100% Built in the USA.