System 4 is designed to remove sebum, fatty acids and environmental deposits, regulate the moisture balance of the hair and protect color.professional care treatment for thickening colored hair visibly thinning.for denser looking hair and restored moisture balancefrees the scalp and hair from sebum, fatty acids and environmental depositshelps improve hair resistance and regulate moisture balancefor a refreshed scalpDirections for use: Shake well before use. Then gently and evenly distribute over the entire scalp. Do not rinse!