2 in 1 Audio Receiver Transmitter: Receiver Mode: for car audio , wired speaker , home speaker , speaker power amplifier , headphone etc. Transmitter Mode: for TV computer projector power amplifier TV , wireless headset headphone , wireless speaker etc. Hands Free Calls: Receiver RX mode and microphone supports hands free calls, 1 key to answer, reject, end a call. (Note: transmitter TX mode does not support microphone) V5.2: Fast response, 3.5mm Aux supports auto reconnection and stable transmission.Turn your wired headset into wireless headset hifi performance, bring you more crystal clear sound. Easy to Use: Plug and play,this V5.2 aux adapter is low power consumption and energy saving, you do not have to look down the phone on the driving. Portable: 9.9cmx2cmx1.2cm/3.90inchx0.79inchx0.47inch,this 3.5mm AUX adapter is small and lightweight which makes it very easy to carry. Specification: Product Model: 2 IN 1 Audio Receiver Transmitter Function: Audio transmitting and receiving version: V5.2 Battery capacity: 120Amh Working range: 10 meters (without any obstacles) Charging time: 2.5 hours (Support using while charging) Use time: 5 hours (music and calls) Standby time: 100 hours Connector: 3.5mm Material: ABS PC material Size Chart: 9.9cmx2cmx1.2cm/3.90inchx0.79inchx0.47inch Package Includes: 1x 3.5mm Aux Transmitter Receiver Adapter (note: The Adapter You Receive with Black Function Key) 1x Power Cable 1x Manual Note: Please allow slightly errors due to manual measurement and different monitors.