Suitable for environments with a medium to high level of noise, The best choice in high frequency noise situations, Smooth telescopic size regulation, Non-conductive, Conforms to EN352, Clips straight into the Zenith helmets without an adapter, Requires KAWAC00003 bayonet adapter for the plasma helmet (sold separately) SNR raing dependant on helmet combination:, Plasma, HP, Superplasma - SNR 25, Zenith - SNR 23