System 4 is specially designed for noticeably thinning, fine, chemically-treated hair. It delivers denser-looking hair while protecting the scalp and providing moisture balance to colored hair. System 4 Cleanser helps to remove follicle-clogging sebum, fatty acids, and environmental residues from the scalp skin, and hair. Cleanses to provide thicker-looking hair. The NIOXIN System 4 Cleanser Shampoo is formulated with Pro-Color Shield technology that helps remove sebum, fatty acids, and other environmental residue from the scalp and hair.