OBAGI Professional C 10% L-Ascorbic acid provides L-Ascorbic Acid, the most bioavailable form of Vitamin C, for optimal skin absorption and results. As we age, our skin doesn’t snap back like the way it did in our younger years, resulting in more signs of skin aging, such as the appearance of fine lines and wrinkles. L-Ascorbic Acid is the active form of Vitamin C and is proven to help reduce the look of fine lines and wrinkles. Obagi Professional-C Serum 10% contains a concentrated formula with L-ascorbic acid (Vitamin C) it is gentle enough for dry or sensitive skin. Recommended for dry or sensitive skin.