... up/down 4,laser pointer,MP3 play 5,LCD diplay mic teaching aids & teaching microphone This ... used on different receiver.3.MIC type:Built-in MIC design,eliminating the line.4.Size:Staff ... a small size, easy to use.5. LCD display power supply,low battery,signal link,volume ... 2.4GHz emitter, microphone and processor are combined in this all-in-one unit, for revolutionary, cable-free convenience.More ...