The N°.9 Bond Protector Nourishing Hair Serum, infused with patented Olaplex Bond Building Technology, is a silicone-free antioxidant hair serum that instantly shields hair from pollution and protects against heat damage while adding satin shine and reducing static and tangles. The N°.9 Bond Protector Nourishing Hair Serum is Silicone free, Sulfate free and PH balanced.