Nioxins cleanser shampoo System 4 for Colored hair with Progressed thinning is the first step of a three part Nioxin regimen, specially formulated to strengthen the hair and amplify hair structure. It prepares hair and scalp for a complete hair thickening treatment. This professional derma-purifying Cleanser Shampoo removes dirt, excessive oil and other environmental residues from the scalp and hair.