A sensitive radio offers FM and AM reception, so that you may listen to music, your favorite sports team or talk radio show. It is also MP3 compatible so you can plug in your iPod and listen to your music while you work. This model uses two AA alkaline batteries (included) and they are replaceable through an external battery compartment. A fresh set of batteries provides about 150 hours of operation. Just in case you forget to turn off your radio headset, we have assured that you do not come back to a dead unit, by incorporating an automatic four-hour shutoff. The sound generated by the speakers is limited to a safe 82 dB level with the use of a gain limiter. Independent testing established a Noise Reduction Rating of 22 dB.