Serum 10 AOX+ utilizes 10% pure vitamin C (l-ascorbic acid) and 0.2% ferulic acid to help neutralize damaging free radicals that contribute to atmospheric skin aging environmental damage and premature signs of aging caused by free radicals from UVA/UVB radiation. Vitamin C is one of the best antiaging ingredients and this is one of the most affordable Vitamin C Serums from Skinceuticals.