Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions, the simplest being fluoronium and fluoroantimonate. The mixture is the strongest known superacid, stronger than pure sulfuric acid by many orders of magnitude, according to its Hammett acidity function. It even protonates some hydrocarbons to afford pentacoordinate carbocations. Like its precursor hydrogen fluoride, it attacks glass, but can be stored in containers lined with PTFE (Teflon) or PFA.