A concentrated anti-aging serum enriched with vitamin C that is suitable for all skin types.Obagi Professional-C Serum 15% infuses your skin with L-ascorbic acid, the only form of vitamin C suitable for topical application. Designed to penetrate deep into your skin, this vitamin C serum provides effective antioxidant protection from UV damage as it brightens away hyperpigmentation and encourages the growth of collagen and elastin fibers.