COSRX Advanced The Vitamin C 23 Serum is a highly concentrated formula containing 23% stabilized pure vitamin C that enhances skin elasticity, brightens the complexion, and reduces wrinkles. Acting as a potent vitamin C booster, it targets dull, rough skin while improving overall skin tone and texture. Designed with a unique two-layer structure—oil on top of the serum—it helps prevent oxidation and delivers a moisturizing finish. Ideal for those experienced with vitamin C and seeking powerful, visible results in a short time, this serum addresses hyperpigmentation, signs of aging, dullness, uneven skin tone, and dark spots. The lightweight texture blends the oil and vitamin C layers seamlessly into the skin, leaving it supple and radiant, while its natural yellowish tint reflects the presence of pure vitamin C and nourishing oils.