The Redken Extreme Shampoo and Conditioner duo is specifically formulated for damaged hair, aiming to provide strength and repair. With a volume of 300ml for each product, this standard-sized set is designed to last for 12 months after opening. Made with biotin as one of the key ingredients, this shampoo from the Redken Extreme product line is ideal for those looking to restore and nourish their hair in the United Kingdom.