The Nentir Nexus
A pocket watch which, instead of telling time, shows the shifting of the planes.
Aldan Vane received this peculiar watch while on his travels in Sigil. The watch tells where the planes are in alignment, rather than the time.
Recently, it malfunctioned. While staying at the Four Winds Tavern in Fallcrest, Vane gave the watch over to a tinkerer who said she would work on fixing it. He hasn’t seen it since.