Level up your colour-care and activate glass-like shine up to 3-days* using the Acidic Color Gloss Shampoo . Now available in this 300ml and 500ml refill duo, your hair will remain glossy and vibrant for longer than ever. This revolutionary technology combines an advanced pH formula and Acidic Shine Complex, so your colour remains vibrant with a professional gloss after every use. Citric Acid works by rebalancing the hair back to its healthiest pH [pH 4.5-5.5], sealing the cuticle, so your salon colour is locked in and protected from dulling agents such as pollution and heat. The sulphate-free formula provides a gentle-lather, smoothing each strand from root to tip, preventing the fading of your hair colour during the cleansing process for more vibrant, healthy-looking hair. With Redken's game-changing Acidic Shine Complex, you can now level up your colour-care by activating a professional gloss at home for glass-like hair. Formulated with a blend of amino acids and conditioning agents, the complex works by depositing glossing molecules across the hair for a mirror-like shine. With every application achieve shine that not only looks but feels healthy, with hair feeling hydrated for up to 72 hours**. *Consumer test using full system of Acidic Color Gloss **based on consumer test - acidic color gloss system of shampoo & conditioner