KASK SC3 is a hearing protector adapted for attachment to a helmet. Fits all helmets with 30 mm slit, e.g. KASK and Petzl. Specially adapted for use with KASK helmets in environments with moderate to high noise levels. SC2 is especially good at dampening strong noise such as Airports, car racing, drilling, etc.! For KASK's helmets in the Plasma series, an adapter art. No. 754000001 is needed as the helmet lacks a slit for hearing protection.