Polyperfluoroethoxymethoxy Difluoroethyl PEG Ether Diisostearate is the diester of Polyperfluoroethoxymethoxy Difluoroethyl PEG Ether (q.v.) and Isostearic Acid (q.v.). See Reported Ingredient Functions-The Cosmetic Drug Distinction, in Regulatory and Ingredient Use Information, Volume I, Part A.