The Lancôme Cils Booster Eyelash Activator Serum intensely nourishes and revitalizes eyelashes from root to tip. Thin eyelashes are prone to damage and require revitalizing care to gain density and length. The serum repairs hair fibers in four weeks and improves eyelash density with regular use. It also acts preventively against eyelash fall for thicker, longer, and stronger-looking eyelashes.