L’Oréal Professionnel Serie Expert Pro Longer, 400 ml, Hair Serums for Women, Have beautiful hair from roots to tips. The hair serum L’Oréal Professionnel Serie Expert takes perfect care of your hair and breathes new life into it. Characteristics: seals and strengthens split ends restores dry, brittle, and damaged hair smooths the surface of your hair gives your hair new strength How to use: Put a small amount of serum into your palms and then work it into your hair. Apply while hair is still damp.