Bluetooth transmitter receiver:
(Transmitter Mode): Transmit audio from non-bluetooth audio sources (TV, PC, CD/DVD player, etc.) to bluetooth headphones via 3.5mm audio cable.
(Receiver mode): transmits audio from the Bluetooth audio source (smartphone, tablet, Bluetooth TV/PC) to headphones/louds/car/homeless audio system via 3.5mm audio cable. (You can only transmit audio, video and files cannot be transmitted).
Switch mode of a key: just press a button to quickly change the transmitter/receptor mode. After the Bluetooth adapter is on, red light in TX mode - Transmitter, blue light in RX mode - Receptor.
USB audio transmission:
(Transmit mode): Transmit audio via USB port (wire transmission), audio is transmitted via 3.5mm AUX port audio cable.
(Receiver mode): The audio is transmitted to the speaker via the 3.5mm AUX audio cable.
Answer or hang calls: in receive mode, when you have an incoming call, press the button to respond to the call free hands