Redken Extreme Length Shampoo 300ml Redken Extreme Length Shampoo with Biotin is for strengthening damaged hair to grow longer and stronger. Extreme Length Shampoo helps prevent breakage and promotes hair growth.It helps hair growth by strengthening damaged hair to grow longer and stronger. Extreme Length Shampoo helps hair growth by preventing breakage so your hair can keep growing longer. -Reduce breakage by 81% when using the full Extreme Length system (shampoo, conditioner & treatment) -Formulated with biotin -Gently cleanses -Helps promote strong hair. Apply daily to wet hair, massage into a lather and rinse. Follow with Extreme Length Conditioner or Extreme Length Leave-In Conditioner.