Physicians Formula Eye Booster Lash 2-in-1 Boosting Eyeliner & Serum's high-tech formula enhances the appearance of lashes while providing the instant definition of a liquid eyeliner, in one easy step! Lash Boosting complex targets the base of lashes where it is most effective. Innovative and easy to use eyelining tool delivers effortless definition. High-tech Japanese formula is long-wearing, water-resistant and smudge-resistant.