Obagi Professional-C Serum 20% contains a potent form of vitamin C that sinks deeply into the skin. This formula offers powerful antioxidant protection. This ingredient forms a shield against aggressors that break down collagen and elastin. Without this collagen and elastin, the skin becomes lax and dull. The lightweight texture does not feel greasy or oily and is suitable for most skin types. Studies show that this anti-aging serum still prevents free radical damage 24 hours after application. Apply this product daily for advanced protection and anti-aging benefits.