What it is: An easy-to-use cake eyeliner for perfecting Laura Mercier's "tightline" technique. What it does:Laura Mercier Tightline Cake Eye Liner is an easy-to-use, cake eyeliner that delivers long-lasting color payoff. The smudge and transfer-resistant formula glides on the lash line smoothly and stays all day long. Perfect for on the go, pop out your favorite shade from its compact and place it in a three or six-well Custom Compact for a customized palette. What else you need to know:All Custom Compacts are sold separately. This product is dermatologist and ophthalmologist tested, and appropriate for contact lens wears. It has been allergy tested to minimize the risk of allergy and irritation.