I am an essential when Colouring because I activate the Hair Colour when you mix us together. I'm not that strong, I will Lighten your Natural Hair Colour 2 Shades so I'm not the Developer for huge Colour transformations. Instead, use me for smaller Colour transformations like lightening from 5 Light Brown to 7 Medium Blonde or 6 Dark Blonde to 8.44 Intense Copper Blonde or 3 Dark Brown to 5 Light Brown. But, if you have 50% or more Grey Hair, I am your soul mate. My Developer formula is designed specifically to grab to your stubborn Grey or White Hairs for the best Grey coverage.