Bluetooth Transmitter, AGPtek Wireless Switchable Portable Transmitter Switch Between Receiver and Transmitter--Simple one-button switch to shift between transmitter(TX) and receiver(RX) mode Bluetooth CSR4.0-- With this technology, youll hear your mp3s without compression. Pair 2 Ultras, use one as a receiver, the other as a transmitter, and experience no lag at all in gaming or watching movies Application-- Bluetooth-enable all 3.5mm media devices (enable Bluetooth receiving: speakers, headphones and more; enable Bluetooth transmission for: MP3, CD / DVD players, e-readers, TVs and more) Battery Life-- Built in 200mah lithium battery for portable use time up to 6-8hours,or fast-charging it through the USB cable Package-- AGPtEK Bluetooth transmitter and receiver adapter, 3.5 mm audio cable, USB charging cable, User manual