... 5,LCD diplay classroom wireless microphones for teacher This model microphone is a bluetooth transmitter,we desined for teachers comfort,who can hang ... can work for 30 hours,standby time :60 days.For handsfree convenience, the 1090 with pendant type microphone If both hands ... . 2.4GHz emitter, microphone and processor are combined in this all-in-one unit, for revolutionary, cable-free convenience ...