Elta MD UV Daily SPF 40 provides powerful protection against the sun's harmful UV rays in a moisturizing formula that is gentle enough to use on post-treatment skin that needs sun protection most. Formulated with hyaluronic acid, a natural chemical that can hold up to 1000 times its own weight in water, this lightweight sunscreen leaves the skin feeling smooth and comfortable. A blend of micronized zinc oxide and octinoxate protects the skin from both UVA (aging) and UVB (burning) sun rays.