This high-potency serum has a slight tightening effect while it helps to even your skin tone and improve fine lines and wrinkles. Its gentle yet effective formula promotes collagen synthesis, which helps protect the skin from future damage by combating free radicals in the environment. It features 3 types of Vitamin C to work in synergy to also help correct existing damage. I like to use this at night as a first layer on clean skin under my favorite moisturizer. ($40)