SensGard SG-31 Lightweight Hearing Protection Band NRR 31dB Noise Reduction Rating of 31dB. Maximum Protection Against Harmful Noise. Minimizes Damaging Noise, While Allowing Speech to Pass Through. Patented ZEM Sound Reduction Chamber Technology. No Batteries Required. Lightweight and Comfortable Head Band. Easily Adjusts to Fit. Quickly Folds for Storage and Portability. Proudly Made in the USA.