WHAT IT IS A professional-inspired treatment that primes hair for deeper repair with the highest dose of patented OLAPLEX technology in any take-home product. It rebuilds hair bonds and strengthens and protects hair integrity. Use as the first step in a two-part system with N.3 Hair Perfector. 5.2 oz. Made in USA. WHO IT'S FOR All hair types, especially those with visible damage. HOW TO USE IT 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 while moving from section to section. 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 (sold separately) 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 & No.5 Conditioner (sold separately).