Primes hair for maximum repair. Our professional-inspired treatment primes your hair for deeper repair, rebuilds hair bonds, strengthens, and protects hair integrity. Use as the first step in a two-part at-home system with No.3 Hair Perfector (sold separately) to strengthen and repair all types of damaged hair. Redesigned for a quick and targeted stream application, the No.0 Intensive Bond Building Hair Treatment features an easy to use nozzle that primes the hair and delivers the highest concentration of the patented bond building technology of any Olaplex at home product. Scientifically Proven: 68% more repair & 3x stronger hair* *When used as a two-part system in just one use. APPLICATION TIP: N°.0 bottle should last 3-6 applications, based on hair length and density. How To Use 1. Apply N°.0 to DRY hair, distributing evenly from root to tip. 2. Work N°.0 into small sections by squeezing the liquid into the hair to be fully absorbed as you go. 3. Lightly saturate. Hair should be damp, not drenched. Let process for 10 minutes. DO NOT RINSE. 4. Apply N°.3 over hair with N°.0 still applied. Comb through and process for at least another 10 minutes. 5. Rinse, shampoo & condition. For best results, use N°.4 Shampoo & N°.5 Conditioner.