This 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 and 3x stronger hair when used as a two part system in just one use. Primes hair to intensify benefits of no.3. Jump starts repair deep within the hair strand. Pro tip brush or detangle hair before applying no.0 so it can easily be absorbed. For thick, coarse, or long hair, work in small sections to ensure each area is fully saturated. To use apply slowly to dry hair, distributing evenly from root to tip. Work no. 0 into small sections by squeezing the liquid into the hair to be fully absorbed as you go. Lightly saturate from root to tip. Hair should be damp, not drenched. Let process for 10 minutes. Do not rinse. Apply no.3 hair perfector over hair with no.0 applied to it, combing through as needed. Let process for a minimum of 10 minutes. Rinse, shampoo and condition. For best results, use no.4 shampoo and no.5 conditioner. Where apply to dry hair, fully saturating each section. When use the two part system with n?.3 once a week or two to three times a week for damaged hair. For all hair types, especially for those with visible damage. Olaplex products are thoroughly tested in house and by independent third party laboratories for safety and efficacy. This product testing includes the industry standard human repeat insult patch test hript, which tests for skin irritation or sensitivity. All olaplex products have passed the hript, meaning the products show no signs of causing irritation, inflammation, or sensitivity.