Gerber Electronic Ear Muffs - GOAEM003 Features: * NRR21dB * Two microphones * Cut off immediately when sound over 82dB * 4-5 times sound amplification * Independent electronic circuit on both cups for better performance * Soft padded headband * Low profile design, light weight * Dual knobs for on/off and volume * Adjustable plastic headband fits most sizes * 3.5mm input jack one side to connect walkie-talkie or cell phone * Powered by 4 x 1.5v AAA batteries (not included) Attenuation Data: Frequency(Hz) 125 250 500 1000 2000 3150 4000 6300 8000 NRR Mean Attenuation(dB) 1.0 15.5 22.2 24.6 33.7 32.4 29 39 39.9 Standard Deviation(dB) 4.3 2.5 2.6 2.6 ..7 2.9 1.9 3.6 3.3 21