Perfluorobutane (PFB) is an inert, colorless gas with a high density. It is a simple fluorocarbon with an n-butane structure in which all hydrogen atoms are replaced by fluorine atoms.
Due to its inertness and high density, inhaling perfluorobutane causes the voice to become deeper. Caution is advised, as heavier gases are difficult to exhale and can lead to suffocation from inert gas. Perfluorobutane has a high global warming potential of 4800.