L'Oreal Professionnel Serie Expert Inforcer Masque for normal to fragile hair. Infused with Biotin and Vitamin B6, hair is strengthened to treat current breakage and prevent future breakage while adding intense nourishment and hydration that won't weigh down strands. Vitamin B6 promotes hair growth and stimulates protein metabolism to strengthen the hair fiber. Biotin stimulates fatty acid metabolism to promote healthy hair development. Use once a week as a deep treatment to promote strength.