The eyelash serum will give you denser, thicker & stronger-looking eyelash fringe. 4ml. Made in France. Self-evaluation test of 100 consumers after 4 weeks: Lancome’s lash serum is ultra-safe for daily use on eyelashes as it has been tested under ophthalmological control as well as on sensitive eyes. Lash Revitalizing Serum helps to repair hair fibers for denser, thicker, and stronger-looking lashes. 1. Beginning with a clean eye area, apply the lash serum along the eyelash line, from root to tip, twice daily. 2. Wait 1 minute and 30 seconds before eye makeup application. Pro tip: For even fuller lashes, apply Cils Booster XL Primer to eyelashes followed by your favorite mascara.