L'Oréal Paris Elvive Hydra [Hyaluronic] is a deeply hydrating hair care range that brings the quenching properties of hyaluronic acid to the hair. A star ingredient in skincare, hyaluronic acid is known for its ability to retain up to 1.000 times its weight in water--in short, it's a hydrating ingredient like no other, capable of restoring hydration and fullness to the hair strand for up to 72 hours.