Nutrafol - BUILD-UP BLOCKER Scalp Microbiome Exfoliating Mask A physician-formulated exfoliating scalp mask with natural ingredients that eliminate impurities and preserve the scalp microbiome. Clinically shown to dissolve excess sebum and balance oil production, remove dirt and product build-up, and visibly improve dryness and flakiness. *color & extension safe. 4 fl oz.