TWS True Twins Wireless Bluetooth Earphones Earbuds with Automatic Charging Case Bluetooth version: V5.2 Support protocols A2DP, AVRCP, HFP, Working voltage: 3.1v-4.2v Charging voltage: 5v-1a Battery capacity of headset: 50mah Storage box battery capacity: 2000mah Transmission distance: 10M / Talk time: 4 hours Playback time: 4 hours / Headset charging time: 1-1.5 hours Charging time of storage box: 1-2 hours / Compatible for all Bluetooth devices and Android and iOS Smart Phones