Primes hair to absorb nourishment for maximum repair. 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, 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.