The 3M Peltor ProTac III hearing protection protects against harmful noises, while allowing you to hear ambient sounds at a sound level below 82 dB. It enhances your ability to communicate with colleagues nearby, hear warning signals, approaching vehicles or machine and process sounds. - Built-in sound modulation function allowing you to hear ambient sounds, such as conversations, machine noises and warning signals - 3.5 mm stereo listen-only input (limited to 82 dB) allowing connection to external devices (e.g. mobile phone, radio, radio broadcasting/reception, iPod) - Voice-guided menu system to avoid having to remove the headset - With the automatic shutdown function, the headset turns off after 4 hours of non-use to save energy; a signal indicates when to change the batteries when their charge level is low - To reduce corrosion caused by sweat, electronic components are located on the outer part of the shell - Bluetooth: No - Operating temperature: -20 °C (-4 °F) to +55 °C (131 °F) (battery use) - Dimensions: Width: 15.6 cm, Height: 11.4 cm, Length: 20.6 cm, Weight: 0.5 kg