Protective helmets particularly suitable for working at altitudes, polyamide fastening strap with a four hole fastening position. Internal structure with six fastening positions, anti-sweat strap, shell of helmet with air ventilation in ABS injection molded, with high impact and compression resistance. Back cover colour orange that gives greater visibility in low light conditions and protects the upper part of the neck . Protection against electrical current of 1000 V AC, 1500 V DC (EN 50365).