Optime II has been developed for demanding noise-hazard environments and muffles even extremely low frequencies to a maximum degree. The sealing rings are filled with a unique combination of liquid and foam. The result is an optimum seal with low contact pressure, which provides snug comfort even during long-time use. Neckband style ear muffs. The sealing rings have ventilation channels and are covered with soft, patterned, hygienic foil. Large space inside cup helps reduce moisture and heat build-up. Optime II is a suitable choice for environments with substantial industrial noise or construction machinery, airports and agricultural work. Conforms to EN 352-1: 1993. Attenuation: SNR 31dB, High Frequency = 34dB, Medium Frequency = 29dB, Low Frequency = 20dB