Medik8 | Intelligent Retinol 6TR Serum (15ml)Medik8's Intelligent Retinol 6TR Serum is ideal for those looking to move up from the Retinol 3TR, this impressive serum has been designed to work during the skin's most regenerative time. It contains 0. 6% time release Retinol and antioxidants to boost collagen production, regulate excessive sebum production and stimulate cell renewal without leaving the skin red and irritated. With consistent use, skin becomes smoother, firmer, and more even in tone.