LIVING PROOF PhD Shampoo 236 ml: A revolutionary shampoo that allows you to wash beautiful, healthy hair. While delivering five benefits to your hair – control, volume, strength, hydration and shine. Perfect hair Day (PhD) is for anyone who wants more perfect hair days. Regardless of whether you have several hair problems or consider yourself to have "normal" hair, PhD is for you who are looking for a balance between control, volume, strength, hydration and shine.