2.4 GHz transmission frequency, Bluetooth wireless, around 33 ft. operating range. Either earpiece can be used alone for one ear monitoring of Bluetooth streamed audio and telephone communications or shared listening (one person listens to one earphone while another person listens to the other) if both earphones are within range of each other. Earphones operate up to 5 hrs. on built-in rechargeable batteries. Charging cradle has built-in rechargeable battery that the manufacturer claims can be used to recharge the earphone batteries approximately 4 times (for more than 24 hrs. of total playtime) between its own charges. Has quick charge feature: 15 min of charging will provide 3 hrs. of playtime. When used with Apple devices running iOS 10, watchOS 3, macOS Sierra or higher Apple OS versions provides the following features: Siri digital voice assistant compatibility, Automatic Ear Detection (pauses music when one AirPod is taken out of ear and resumes when it is put back, and stops music when both are taken out), automatic connection to unlocked iPhone and to all cloud connected Apple products associated with that account, battery status check via holding the AirPods next to your iPhone or asking Siri “How’s the battery on my AirPods?”