Walker's Razor Rechargeable Electronic Earmuffs - The Razor Rechargeable earmuff features sound activated compression, frequency tuned for natural sound clarity and full dynamic range HD Speakers for clear balanced sound. Low Noise/Frequency Tuned For Natural Sound Clarity 300 MAH (40 Hours Of Battery Life) USB Charging Port Full Dynamic Range HD Speakers For Clear Balanced Sound Sound Activated Compression Sound Dampening Composite Housing 3.5mm Audio Jack USB Charging Cable Included 23 NRR