The Kérastase Première Sérum Filler Fondamental is a leave-in serum designed to treat hair brittleness. This serum perfectly enriches your existing hair care routine, providing essential nourishment, strengthening hair, and restoring its shine. Its caring formula promotes natural regeneration, breathing new life into dull and damaged hair. With regular use, you will achieve strong, shiny, and visibly healthy hair. It provides deep hydration, nourishes hair from root to tip, restores dry, brittle, and damaged hair, and offers thermal protection. The formula is free from sulphates. To use, apply to shampooed, damp hair. Do not rinse. Blow-dry and style as usual.