1.amp,receiver,RS232,USB 2.linking time 3 seconds 3.5 ... amplifier, teaching aid equipment amp Function/ Strong pointThis teaching aid equipment amp is 2.4g wireless audio system used in classroom for amplify ... .RS232 jack,could be connected with PC,central control,USB system.5.Five line wired MIC input with 6V power supply ... you have any question ,Thanks a lot! teaching aid equipment amp