Olaplex no9 nourishing hair serum. A weightless, antioxidant rich, multi benefit serum ABOUT Nº.9 The anti-damage hair shield Seeing dull hair, tangles, or poor style retention? These could be signs of pollution or heat damage. Protect your hair from daily damage with this weightless, leave-in, silicone-free hair serum to shield hair from pollution for 48 hours and provide heat protection up to 450°F (232°C). With antioxidant-rich Red Algae Extract and scientifically proven OLAPLEX® Bond Building Technology™. Visible Hair Benefits • Satin shine & softness • Style memory & bounceback curls • Anti-tangle & anti-static