Awei AT7 Bluetooth wireless headphone stereo surround speaker with microphone headset

pgraded Li-polymer batteryLonger battery lifeMicro-SD card are supportedBluetooth version: 5.4Bluetooth protocols: a2dp 1.3.2\avctp 1.4\avdtp 1.3\ avrcp 1.6.2\ hfp 1.8 \spp 1.2\rfcomm 1.1\pnp 1.3\ hid 1.1.1\sdp core5.3\l2cap core 5.3Channel system: stereoBattery capacity: 600mAhCharging time 2.5hPlay time ≈70hCall time ≈40hHorn diameter: 40mmHorn impedance: 32ΩHorn sensitivity: 121±3dBBest transmission distance: <1mMaximum transmission distance: 10mBluetooth operating frequency: 2.402GHz~2.480GHzWearing method: head-mountedCharging interface: Type-CUser manual: Chinese and EnglishAccessories: USB charging cable, user manual