Discover Obagi’s bestselling Professional C® Serum 20%. Our highest concentrated Vitamin C serum helps minimize the appearance of fine lines and wrinkles. Daily Use of Vitamin C Proactively fortifies the skin defenses against environmental assaults. Encourages skin to rebound from previous, visible damage for an improved appearance of fine lines, wrinkles and uneven skin tone. Strengthens skin defense with a powerful antioxidant that helps skin appear younger for longer.Key Ingredients: Known as the purest form of Vitamin C, L-ascorbic Acid helps neutralize free radicals, minimize the look of fine lines and wrinkles, and brighten skin tone.