The UFO (Ultimate Fuzz Octave) is a hand-built octave fuzz pedal in the vintage style, but the octave effect has its own footswitch so you can choose if you want to add it to the fuzz, which comes in two flavours - vintage and modern - selected with a toggle switch.
Vintage is thick and creamy 60s-style fuzz, but with a nice raw edge, delivered via a tone knob that can dial in some throaty upper-end presence to cut through the mix.
Switched to modern, you instantly get a fatter bottom-end and more output, which makes the pedal more willing to take off into harmonic feedback. The upper-octave effect is a real treat.
It's mixed proportionally to be fairly prominent, but you can tame it a touch with the tone knob if desired, and it works just fine all over the neck - no matter which pickup you are on - just flick it in to add extra interest to your solos and riffs.