Cosrx The Niacinamide 15 Serum (Suitable For Oily & Combination Skin Type) 20ml.A Total Acne Care Serum containing highly concentrated niacinamide (15%) for mild exfoliation, sebum control, and antibacterial effects, giving you a smooth, fresh, problem-free skin.Effectively treats acne, including papule, pustule, cyst, and at the same time strengthens the skin barrier.