L\'Oréal Elvive Fibrology Thickness Creation Double Serum is the secret to thicker hair. Its 2 formulae are kept in separate containers and mixed at the last moment to release their full potential for a complete action on the fibre: - The Thickening serum enriched with Filloxane, which penetrates the hair fibre, and expands for a thickening effect. Instantly hair has 80% more body & bounce. - The Perfecting Serum smoothes the surface of the fibre for silky, glossy hair. A complete treatment for hair lacking thickness, when used after Fibrology shampoo & conditioner.