ETvalley Wireless Bluetooth Receiver Aux Bluetooth Transmitter Bluetooth Adapter for Speakers and Cars with 3.5mm Stereo Output, Black Upgrade your speaker system or car audio system easily with the portable Bluetooth receiver to feature Bluetooth connections. 2-in-1 device. The Bluetooth car kit can receive (RX) and transmit (TX) the Bluetooth signal. Change between the modes quickly with the switch button. Rechargeable built-in battery, chargeable through USB connection. The multifunctional button of the Bluetooth speaker adapter lets you answer phone calls or control the music on the receiver. The wireless Bluetooth adapter is compatible between two devices, if one has a 3.5mm audio-plug and if the other has a Bluetooth receiving/sending feature.