The reason why sodium hyluronate can go the distance? Its small size. "Sodium hyaluronate is the salt form of hyaluronic acid," notes Dr. Caroline Chang of the Rhode Island Dermatology Institute. "It is smaller than HA, which allows it to penetrate the skin further." It's also more stable than its larger counterpart, since it is less susceptible to oxidation, she continues—but don't go and rule out good, old HA for good. "Both hyaluronic acid and sodium hyaluronate bind water and are therefore both good ingredients for hydrating the skin," she affirms. As for where you can find this workhorse ingredient? Find it embedded into the formulas of a few of our favorite products, below.