... :bluetooth 3.Warranty:3year,class-D amplifier Audio Equipment(power amplifier module)Feature/Function:1.Technology:Built - in 2.4G ... 3seconds.4. It can also automatically search for the transmitter signal and locked.5. Features:No interference, no string frequency ... With two line advanced audio output,two line windows media signal output.14.Application: multimedia room, Multi-function Room, classroom ...