Hearing protector provides protection against harmful noise by allowing ambient noise to be detected. Built-in level-dependent function allows the wearer to hear ambient noises such as conversations, machinery and alarms. With a 3.5mm stereo jack, you can connect it to your mobile phone or two-way radio to hear the call directly in your ear. Auto power off: after 4 hours from the last operation, the device will automatically switch off. Low battery alarm when the battery is low. Voice menu system - no need to remove the headset. Battery type AA. Battery life 100 hours. Connection type 3.5mm