Specification: Bluetooth version:4.0 Valid distance: UP TO 10 meters Battery duration:about 5 hours Charging period:about 1.5 hours Product size: 45mm x 11mm Introduction of multi-point function: It will searching new device after power on,and the blue lights flashing alternately. One of the blue light on after connect one device successfully. It will connect one bluetooth device automaticly, push the power on button if the 2nd speaker need to search. Both of the blue lights on after two speakers connect successfully. The red light's on when charging and off with full charge. Power off: long press 2 seconds. Package Include: 1 x Bluetooth 4.0 audio transmitter 1 x 3.5mm audio cable 1 x USB cable1This for bluetooth transmitter can help transmitting stereo audio wirelessly from your non-bluetooth audio sources to your for bluetooth-enabled headphones, speaker or receiver. In this way, you can enjoy high quality music or late night shows without disturbing your loved ones while they sleep. 2No lip?sync delay for stable audio transmission. You can comfortably enjoy high clarity stereo sound while watching TV, movie, video. 3This for bluetooth transmitter will be power off to reset when you charge it, you can power it on to get continue to work while charging. 4This for bluetooth transmitter has good compatibility with most for bluetooth headphones. Easy to be hide behind somewhere home and carry in road trip or flight to enjoy music. 5The product do own long play time, which means you can enjoy music for almost the entire day before the next recharge.