Even when it is healthy, thin hair is more prone to aggressions, it tends to break easily and to form split ends. Having a diameter 20% smaller than that of normal hair, its structure is extremely fragile and far more delicate. The elements – like humidity, which weighs it down, or the sun, which dries it considerably – visibly damage this type of hair. Program 4 has been formulated to add volume and lightness to thin, fragile hair with split ends. Its strengthens the roots, redefines hair structure and adds volume, allowing to create one’s favorite hairstyles.