This shoe was designed for a charity auction to promote Undertow, a Portland trio of artists. They had a really nice display which consisted of a fish tank with these shoes in them. When the charity auction was up, most blog sites stated that these were a 1 of 1. That's not exactly the case, but they still exist in really small numbers. The detailing on these Promo pairs are incredible. The clear panels are backed with a bubble-like design, and the bottom aqua-tone makes it seem like you're walking on water...Well, not really.