QuieTunes Rechargeable FM Radio Earmuffs with 25 dB Noise Reduction Rating. Elvex QuieTunes ear muff with a built in FM stereo radio offers the following features: Hearing protection is the primary objective and QuieTunes provides 25 dB Noise Reduction Rating. Tested by an independent and certified laboratory. An electronic control limits the sound produced inside the headset to 82 dB, keeping the sound level inside the headset below the level mandated by OSHA. A sensitive stereo radio covers the wavelengths between 88MHz and 110MHz. QuieTunes is equipped with a balance control, allowing adjustment of left-right speaker balance. An auto off switch will turn off the headset after four hours of continuous use, in order to extend the battery life. QuieTunes comes with a charger, allowing the unit to recharge overnight for 40+ hours of use. This feature may save a user as much as $25.00 - $50.00 per year in battery cost. The recharge port can also be used to connect other devices to the QuieTunes, such as CD-players and communications radios. The input signal will override the FM radio, which cannot be heard when an auxiliary device is used.