The Vacuum Helmet is a device used by Fawful in Mario & Luigi: Superstar Saga and Mario & Luigi: Bowser's Inside Story. It is used to get Fawful around and attack the Mario bros. It is also noticed to have many functions and is Fawful's most used invention.
The Vacuum Helmet has many functions, and is primarily used by Fawful to fly around or hover. The Vacuum Helmet's nozzle can both shoot fiery balls of energy at Fawful's opponents and vacuum up other things, which are then stored within the Vacuum Helmet.
Mario & Luigi: Bowser's Inside Story introduces more functions, including the Vacuum Helmet's ability to function independently from Fawful. It is also revealed that the Vacuum Helmet's nozzle can morph into a kind of basket, inside of which Mario or Luigi can be trapped and drained of their HP. Fawful can also fly using the helmet. While Fawful is fighting Bowser, he may use his Vacuum Helmet to avoid some of Bowser's attacks or he can revive some of his own HP. The Vacuum Helmet also morphs its nozzle into what looks like teeth, allowing Fawful to grab onto objects and swing from them. At some point, the Vacuum Helmet will fly above Fawful's head on the top screen, where Bowser can use his vacuum ability to suck it up into his body, where the Bros. will fight it. After taking a certain amount of damage, the Vacuum Helmet will explode and cease to exist, making its last appearance.