The Sebastian Professional Penetraitt Overnight Rescue Repair Serum for Damaged Hair is designed for nights when your hair is in need of a reset. The leave-in serum works as you sleep, wrapping strands in nourishment to help them feel smoother and more manageable by morning. The lightweight texture absorbs quickly, cushioning the hair with a soft finish that supports a hydrated-looking surface. Simply apply to dry hair before bed and let it work overnight, no rinsing required.