Product description: - Serum prepares damaged hair for maximum repair. Our professional-inspired treatment protects your hair for deeper repair, rebuilding, strengthening, and protecting its integrity. Use it as the first step in a two-part at-home hair treatment system with Olaplex No. 3 Hair Perfector (sold separately) to strengthen and repair all types of damaged hair. Scientifically proven: 68% more repair and 3 times stronger hair when used as a two-part system in just one use. How to use: Used as the first step in at-home hair treatment. Distribute the serum on dry hair from roots to ends and leave for 10 minutes for best results. It is recommended to use it with Olaplex No. 3 Hair Perfector and leave for an additional 10 minutes. When: Once a week or two to three times a week for damaged hair. Where: Applied on dry hair and fully saturated. For all hair types, especially for those with obvious damage. Product size: 155ml