Features: Bluetooth-compatible mode: Press and hold the button for about 2 seconds, when you hear the voice prompt, the Bluetooth-compatible is turned on successfully, then turn on the Bluetooth-compatible function in the phone, and connect to the power bank to use. U disk mode: Insert the U-disk into the OUT1 port, and then long press the button to auto-play (the file size format will affect the playback sound quality and sound volume). operation: clicks to display the power or adjust the volume, double-click to turn on the LED light; Long press to turn on (or turn off) the Bluetooth-compatible function (USB disk playback). Battery requirements: 3.7V/26650 battery (internal resistant less than 50 milliohms, the voltage of each cell must be between 3.3-4.2V), do not use pointed batteries, Modification or putting in other batteries that do not meet the requirements is not supported! ) Specifications: Material:Plastic Color:Black,White,Green,(Optional) Model: Q16 Capacity requirements (Capacity): 3.7V/2000-34000mAh USB output (Output): 5V/2.1A Type-C input (Input): 5V/2.1A Mirco input (Input): 5V/2.1A Number of batteries: 4 flat 26650 batteries (26x65mm, voltage 3.5-4.2V) Package Includes: 1x Power Bank Box(Battery,Charging cable is not include) Screws note: Please allow 1-2cm errors due to manual measurement,pls make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.