OLAPLEX No.2 Bond Perfector is step 2 of 2 in the professional Olaplex system, applied at the shampoo bowl after the chemical service has been completed and rinsed. It finds single sulfur-hydrogen bonds and cross-links them back together — completing the repair that No.1 begins. No.2 is a bond multiplier, not a conditioner, and is necessary after every Olaplex service. This is the 525ml professional back-bar size.