A vacuum mask was a piece of equipment designed to allow the wearer to operate in vacuum conditions.
It was an emergency measure to protect the wearer against a lost of atmosphere aboard a spacecraft or space station. When sensors detected a lack of breathable atmosphere, the mask automatically supplied the wearer with ten minutes of breathable air. It could not be worn simultaneously with a standard helmet or face-mask.
It was commonly worn or carried by people who frequently worked in space. Although they could not replace space suits, vacuum masks were known to save crew-members trapped in compartments that lost atmosphere.
- Star Wars: Knights of the Old Republic (First appearance)