The SkinMedica Age Defense Retinol Complex, otherwise known as the Retinol Complex 1.0, is a active ingredient rich serum. The main benefits that this product offers, according to the brand are enhanced skin tone and texture and reduced appearance of fine lines and wrinkles. While 1.0 may seem like a relatively low percentage of an active ingredient, this is actually the strongest retinol product that SkinMedica offers, and for good reason. Retinol is an incredibly potent active that can be quite irritating for some during the first few months of use. In order to lessen this irritation, SkinMedica actually offers three different options in their Retinol Complex range, starting out at a 0.25 concentration. In order to minimize irritation, while also seeing the best results, we recommend starting off with the lowest concentration a few times a week to see how your skin reacts. As you skin adjusts, you can gradually work towards applying the product every night.