Hydrogenated castor oil PEG-8 esters is the ester of hydrogenated castor oil with polyethylene glycols (the number 8 after "PEG-" indicates the number of molecular units -CH2-CH2-O-, here 8 molecular units) and is used in cosmetic formulations. The ester acts as a viscosity regulator (increases or decreases the viscosity of cosmetic products) and as a skin care product. "Hydrogenated" means treated with hydrogen (hydrogenated).