Medik8 H.E.O. MASK 50mlx2H. E. O. Mask takes a fundamentally scientific approach to optimal maximum skin moisturisation to deliver clinically proven skin hydration, moisture retention and barrier support both instantly and over time. The three key pillars of moisturisation humectants, emollients and occlusives (H, E and O) are combined in an expertly optimised ratio to dramatically improve the appearance of dryness, dullness, fine lines and wrinkles while you sleep. H. E. O.