The Niacinamide 15 Serum with Acetyl Glucosamine + Zinc PCA - The Niacinamide 15 Serum with Acetyl Glucosamine + Zinc PCA from COSRX is a highly concentrated serum that combines the maximum concentration of niacinamide with optimal ratios of synergistic ingredients for total acne control.BenefitsN-Acetylglucosamine (NAG) : Works in synergy with niacinamide to effectively fade hyperpigmentationAllantoin : Promotes collagen synthesis to facilitate skin regenerationNiacinamide : Provides total acne care by controlling sebum production, soothing acne inflammation and diminishing post acne scarsZinc PCA : Inhibits inflammation and promotes recovery of damaged skin - The Niacinamide 15 Serum with Acetyl Glucosamine + Zinc PCA