Olaplex Bond Perfector No 2 67.62 oz Half Gallon
Step 2 of the Olaplex Salon Treatment, which is the most used step in the treatment.  This is a back bar size. 
OLAPLEX Bond Perfector No. 2: After rinsing haircolor, apply for a minimum of 5 minutes then rinse, shampoo, and condition. You can even leave it in the hair to use as a cutting lotion.