Very rare Ibanez OT10 Octave Pedal from the 1980s. Inherited from my father-in-law, but I'm not really using it, so I'm letting it go. Always kept in a smoke-free environment. Very good condition, a couple scuffs and the sticker is missing from the back, but I tested it, and it works as it should. Here's some info from the manual that I found online:

The Ibanez OT10 lets you fatten your sound considerably by adding an identical line exactly one octave below the original melody for a rich unison effect. The responsive, natural octave sound produced by the OT10 not only matches the frequency range of guitars perfectly but is also excellent for bass. In addition, the EDGE control allows you to alter the timbre of your instrument's treble. In fact, you can even use it to create a sound one octave above the original. For exciting hard rock riffs, try combining the OT10 with distortion-type effects. And by simply mixing the DRY and EFFECT sounds, your guitar or bass becomes a fat synthebass.