COSRX The Vitamin C 13 Serum is a potent antioxidant serum formulated with 13% pure vitamin C (ascorbic acid) to brighten the skin, fade dark spots, and even out skin tone. Its lightweight texture absorbs quickly, helping to boost radiance and reduce the appearance of fine lines for a more youthful, glowing complexion. Suitable for all skin types, this serum delivers powerful results while maintaining skin hydration and smoothness.