Universal Key

Universal Key is a master key owned by Emperor Pilaf, who keeps it under his hat. It is seen in the Dragon Ball episode "The Nimbus Cloud of Roshi".

Overview
The Universal Key is a projector that allows Pilaf to select any key in the world and, as he claims, open any lock in the universe. Whether or not this is true is questionable as in its only use Pilaf tried to open the door to Kame House and, even after he selected the right key, he had trouble opening it so that Mai and Shu had time to sneak in through an opened window and open the door from the inside.