KN319 ia a 2 in 1 BT Transmitter & Receiver. As a BT Audio Transmitter, it can be connected to the audio devices without BT function via the included 3.5mm Audio Plug, changing these audio devices into BT-enabled audio devices, and making it work with BT-enabled Headset and Speaker. As a BT Audio Receiver, KN319 can change the traditional Car Stereo systems and Home Audio System into BT-enabled ones, and easy to pair with BT-enabled Smart Phones, laptop, tablet, etc. With this product, you can greatly enjoy music from your phone, laptop, tablet without the hassle of cables. This 2 in 1 BT Transmitter & Receiver will give you much fun and convenience.Features:Receiver Mode:Change the traditional Car Stereo system or Home Audio System into BT-enabled ones. After paired, play music wirelessly from your BT-enabled Smart Phones, Laptop, Tablet and more.Transmitter Mode:Connected to the audio devices (such as MP3, MP4, TV and PC, etc.) without BT function, changing them into BT-enabled ones, and making it work with BT-enabled Headset and Speaker.Strong Compatibility:With the included 3.5mm cable and 3.5mm to 2RCA cable, this Receiver Transmitter adapter can be widely used on your computer, laptop, home stereo system, headphone, smartphone, MP3 player, CD player, etc.Low Consumption:Built-in 200mAh rechargeable battery ensures 5-6 hours of working time, you can enjoy wireless music all day long. Easy connection, no driver needed, plug and play.Convenient to Use:Switch between transmitter and receiver modes with the simple flick of a switch. Weighs only 18g (0.63oz), easy to carry in your backpack or laptop bag and take it on-the-go.Specifications:Model number: KN319BT Version: 4.2Protocol Supported: A2DP, AVRCP (receiver mode only)Transmission Distance: 10m / 33ft (open space)Battery: Built-in 200mAh Rechargeable Li-polymer batteryContinuous Use Time: 6 hours (Receiver Mode) / 5 hours (Transmitter Mode) Time: about 2 hours: Micro USB 5VColor: BlackMain Item Size: 4.4 * 4.4 * 1.2cm / 1.73 * 1.73 * 0.47inMain Item Weight: 18g / 0.63ozPackage Size: 11.2 * 7.6 * 2.3cm / 4.40 * 2.99 * 0.90inPackage Weight: 77g / 2.71ozPackage List:1 * BT Audio Transmitter & Receiver1 * 3.5mm Audio Cable1 * RCA Cable1 * USB Cable1 * User Manual (English / Chinese)