Sound activated compression. Anti-bacterial Agent. NRR- Noise Reduction Rating of 24db. Ultimate acoustic real ear pads. Power source 2 "AAA" batteries. 9x enhancement, 50db of power Two high-definition digital channels for unsurpassed sound quality and speech clarity that only digital technology can produce. 4 wind resistant, high frequency, stereo microphones for precise sound directionality. AFT-Adjustable FrequencyTuning. Digital signal processing. Two independent volume controls.