Skinceuticals c+aha exfoliating antioxidant treatment a unique 2-in-1 skin care to combat aging skin both inside & out 15% concentration of pure l-ascorbic acid defense skin against uv rays and stimulate collagen production inside 10% concentration of hydroxyl acids exfoliate surface skin makes skin smooth for a more youthful appearance infused with glycolic acid & lactic acid to lift away rough outer skin layer leaves you a newer - younger-looking skin