COSRX The Niacinamide 15 Serum is a lightweight, water-based serum formulated with 15 percent niacinamide alongside zinc PCA, acetyl glucosamine and allantoin. It is designed to help refine the look of enlarged pores, regulate excess sebum, and even out skin tone and post-acne marks over consistent use. The gentle, fragrance-free formula is free from alcohol, parabens, sulfates and silicones, making it suitable for oily, acne-prone and sensitive skin types. After cleansing and toning, apply a few drops to the face and pat in gently, following with a moisturizer. A good choice for anyone dealing with visible pores, oiliness or uneven texture looking for a straightforward, no-frills niacinamide serum.