I used Olaplex 3 - 7 today. I used the 3 as a pre-poo treatment. I used number 4 as my shampoo and the 5 as a rinse out conditioner. The shampoo was gentle on my hair. It was very sudsy but not stripping at all. I followed up with the rinse out conditioner which made my hair smooth and soft. I followed that up with the leave-in conditioner. At the end my hair felt strong and moisturized.