Poltergust 3000

From Mariopedia

The Poltergust 3000 is an invention of Professor E. Gadd used by Luigi in Luigi's Mansion. It is essentially a modified vacuum cleaner, red in colour, that Luigi wears on his back. Its function is to suck up the many ghosts of the mansion, which must first be scared in some way by the player. Upon releasing the Boos partway through the game, it is learned through what King Boo says that the Boos fear the device.