Adam Wilber is known both as a magician and inventor, creating tricks and gadgets for Ellusionist like Solved (a magic Rubik's Cube) and Pyro (a wrist-mounted flame shooter). On the season four finale of Penn & Teller: Fool Us, Wilber brings a tiny device with him that allows him to magically change a single dollar into a legitimate $100 bill, complete with a random assistant's signature intact. Watch the video above, and try to see if you can figure out what Penn & Teller couldn't.

For the other acts from the finale, check out the videos below:

Patrik Kuffs hooks a contraption on top of Allison's head:

Todd Lamanske does a wonderful card trick:

And Hector performs shadow magic: