3M Peltor Optime II Ear Muff 31d B Sound Noise Reduction Folding-headband Ref H520F-409-GQ.- Ventilation channels covered with soft, patterned, hygienic foam.- Developed for demanding noisy environments & muffles even extremely low frequencies to a maximum degree.- 31d B SNR.- Hi-Viz.- Folding headb&.- Optime II Earmuff.- Optimum seal with low contact pressure.