... 9001 3.sensitivity:86db,compatibility 4.design for teacher comfort headphone with microphoneFunction:1.Multichannel :It has more than 1000 transmit channels ... (microphone)can be used in a different receiver.1.MIC:headphone, collar or clip,ear-hanging MIC.2.Small size,lightweight ... any other MIC.4.LED display charging status,balanced battery,volume.5.Page turner,USB upgrading.Lithium battery.6.It can ...