Wella's purest permanent hair color ever with ME+ Technology Koleston Perfect is the first professional hair color brand to feature breakthrough technologies boasting: Pure- balanced color results with natural depth and shine ME+- up to 60x less likely to develop a new allergy to hair color Reduce the formation of free radicals for irresistible hair quality Simple 1:1 mixing ratio Up to 100% grey coverage Offers Up to 100% grey coverage Offers Up to 3 levels of lift How To Use: Mixture ratio: 1 part Koleston Perfect Hair Color to 1 part Welloxon Perfect Developer. Mix well.