The Cosrx The Vitamin C 23 Serum is a high-potency vitamin C serum that contains 23% pure ascorbic acid to improve uneven skin tone and provide brightening benefits for a clearer and healthier complexion. Recommended for those with concerns about pigmentation, dull skin tone, and signs of aging, this serum harnesses the power of vitamin C along with other nourishing ingredients to target imperfections and revitalize the skin.