Kerastase Premiere Anti-Frizz Hair Repair Serum is a professional leave-in treatment that repairs and strengthens damaged hair while delivering lasting frizz control. This lightweight formula smooths, reduces split ends, and protects against heat up to 450°F, making it ideal for blow-drying, straightening, or curling. Enriched with bond-repairing technology, it penetrates the hair fiber to improve resilience and shine. Clinically proven to deliver 3x smoother hair and 85% more shine (vs. unwashed hair), it also repels humidity to keep styles sleek and polished throughout the day. Perfect for all damaged hair types, this serum is an essential step in any haircare routine to restore strength, shine, and manageability. Easy to use—simply apply to towel-dried hair, leave in, and style as desired for a salon-quality finish at home.