Olaplex rebuilds hair bonds, strengthens and protects hair integrity. Use as the first step in a two-part system with N°3 Hair Perfector. Scientifically Proven 68% more repair & 3x stronger hair when used as a two-part system in just one use! Tip: N°0 bottle should last 3-6 applications, based on hair length and density. How To Use: Apply the No. 0 to clean dry hair. Comb the product through to ensure saturation. Wait 10 minutes, then apply Olaplex Nº.3 Hair Perfector directly on top of Nº.0. Comb again to saturate thoroughly, then let the treatment sit for another 10 minutes. This treatment is a minimum of 20 minutes, though, just like the Nº.3 on its own, more significant results occur when keeping it on longer! Once completed, rinse, shampoo, and condition. We recommend Olaplex Nº.4 Shampoo and No.5 Conditioner.