Introducing RedKen The Color Extend Magnetics Shampoo. Choosing the right product for your color-treated hair can be confusing. Discover Redken’s Color Extend Magnetics, a gentle cleansing range for colored hair, made with RCT protein complex to protect hair. The exclusive new RCT Protein Complex treats hair from the root to the core to the tip, giving all 3 levels the custom nourishment they need.