Aluratek's Universal Bluetooth Optical Audio Receiver and Transmitter is the one and only adapter you will need to add Bluetooth streaming functionality to your home entertainment system or stream music to your Bluetooth headphones and speakers. The dual receiver - transmitter features a built-in rechargeable battery so you can enjoy wireless audio receiving and transmitting up to 33 feet for up to 15 hours on a full charge. ABC02F remembers up to four Bluetooth devices and can stream two headphones simultaneously in transmitter mode. Dual Modes - Receiving and Transmitting Simply flip the switch on the unit to enable either Bluetooth Receiving or Bluetooth Transmitting. Rx (Receiving): Use the receiving function to stream music wirelessly from your computer, smartphone, or tablet to any audio device with an AUX IN (3.5 mm) port such as stereos, car stereos and speaker docks. You can also connect to home stereo receivers via the RCA IN ports using the included RCA-Y cable or via the SPDIF IN port using the included digital optical audio cable or even connect a pair of wired headphones directly to ABC02F. No need to throw out your old stereo or wired headphone. Keep them alive with Bluetooth connectivity and enjoy the benefits of cable-free music and audio. Tx (Transmitting): Use the transmitting function to Bluetooth enable any audio output device with an AUX OUT (3.5mm) port such as computers, TVs, walkman, CD player and MP3 players to a Bluetooth enabled device like Bluetooth headphones, Bluetooth earbuds and Bluetooth speakers. You can also connect to home stereo receivers via the RCA OUT ports using the included RCA-Y cable or via the SPDIF OUT port using the included digital optical audio cable. ABC02F allows for two Bluetooth headphones to be paired at the same time so you can stream to both devices simultaneously.