Hair mask for long, damaged hair. The Kérastase Résistance Masque Extentioniste is ideal for strained, long hair. Creatine nourishes and smoothes the hair structure and gives more stability and vitality. Maleic acid strengthens hair to restore the hair texture. Damage is repaired at the hair structure. Intensive moisturizers provide suppleness. The products of the Resistance Extentioniste line build up brittle and damanged hair strands from the inside out and give them strength