Kérastase Repairing Anti-Frizz Filler Serum is a lightweight leave-in treatment that, when used with the Première routine, supports inner repair* of all damaged hair types, leaving it glossy and supple. Processed hair absorbs up to 3x more calcium from water than untreated hair, leading to a damaging calcium overdose. This serum has a dual action: its light, balmy texture seals cuticles to shield the surface while coating the fibre to help fill external damage. Hair is protected from hard water calcium, humidity, and heat up to 230°C.* Frizz is eliminated, leaving hair smooth, supple, and easy to style. For best results, use with the full Première routine: 1️⃣ Start with the Decalcifying Pre-Shampoo Treatment 2️⃣ Apply Decalcifying Repairing Shampoo (without rinsing) 3️⃣ Follow with conditioner or mask 4️⃣ Finish with the Anti-Frizz Filler Serum Recreates up to 99% of hair’s original strength | Up to 72H Anti-Frizz