Product parameters: Drive unit: Balanced Armature Bluetooth version: Bluetooth 5.0 Mode of operation: touch Waterproof rating: IPX7 Headphone battery capacity: 40mA Charging box battery capacity: 350mA Headphone working time: about 7 hours (including charging box about 21 hours) Charging box to charge the headset: 3 times Chip: QCC3020 Support apt-x:yes Connection distance: 20 m Touch function: answer/reject calls, play/pause songs Speaker impedance: 22Ω Double Balanced Armature: 60Ω Frequency response range: 20HZ-20000HZ Charging interface: TYPE-C Bluetooth protocol: A2DP, AVRCP, HFP, HSP Bluetooth decoding format: SBC, ACC, APT-X