Obagi Professional-C Serumsâ„ Your skin deserves all the protection you can give it from daily exposure to the sunâs damaging rays and environmental conditions that cause premature aging. Visible signs of aging, those fine lines and wrinkles, are caused by tiny molecules known as âfree radicals.â Free radicals dramatically multiply with exposure to sun, air pollution and other environmental assaults, ravaging skin cells and breaking down collagen that gives skin its youthful resilience. How It Works Obagi Professional-C Serums use advanced scientific formulas developed and tested by leading Vitamin C experts. Obagi Professional-C Serums offer maximum daily antioxidant protection and greater penetration than other Vitamin C products. The greater the penetration, the greater the antioxidant benefit to your skin. Vitamin C neutralizes free radicals to prevent skin cell damage. Professional strength Vitamin C can give your skin the superior protection it needs to: Prevent premature signs of aging, including fine lines and wrinkles Protect against future damage Stimulate collagen production for firmer, more resilient skin Lighten and brighten skin for more even tone Professional Strength Concentrations Obagi Professional-C Serum uses stabilized L-ascorbic acid - the only form of Vitamin C that can be effectively absorbed by the skin. Speak with your Skin Care Specialist to choose from four concentrations to determine which one is right for your skin. 20% Highest concentration of L-ascorbic acid 15% All skin types 10% Dry, sensitive or reactive skin 5% Protection for the sensitive eye area Pro-C Serum 20% Pro-C Serum 15% Pro-C Serum 10% Pro-C Serum 5% Â