Skinceuticals CE Ferulic is a truly revolutionary skin care product. The first antioxidant combination to market designed to deliver advanced environmental protection against photoaging, Skinceuticals CE Ferulic has been a best-seller since its debut on the skin care market decades ago. Studies show its 15% L-ascorbic acid and 1% tocopherol combination provide advanced environmental protection against damaging free radicals, increase firmness, and replenish lipids to visibly reduce wrinkles. Even better, once absorbed, Skinceuticals CE Feruliccan't be washed or rubbed off. It remains effective for a minimum of 72 hours. I personally use it intermittently with my own FutureDerm CE Caffeic Serum, and love them both!