WIDE APPLICATION: USB volume control knob is compatible with multiple systems, supports for Android and systems, and is compatible with mobile phones, tablets, laptops, and desktop computers. FUNCTIONS AND USES: USB volume controller can directly control volume of computer , can be customized, support shortcut keys.( Note: Custom functions require editing software, please contact customer service for editing software.) 2.4G+Bluetooth+wired version: The three-mode model supports wired connection, Bluetooth connection and 2.4G connection. When connecting to Bluetooth, the main device must have Bluetooth function. 2.4G and receiver are connected one by one, and you can use it by inserting it, and it pair automatically. Built-in large-capacity lithium battery with built-in charging function. EASY TO USE: There is no need to install any drivers or software on your computer to drive this volume regulator, and can be used after plugging in device. Custom knob, the knob can be defined as any key on keyboard, or as volume up and down, previous song, next song, play and pause, mouse wheel, etc. Item Type: USB Volume Control Knob Features: Custom; Support shortcut keys Support: For Android systems, systems How to Use: 1. Rotate left: Volume down 2. Rotate right: Volume up 3. the knob: Pause/play 4. the knob and rotate left: Previous song 5. the knob and rotate right: Next song Color: Black Material: ABS+acrylic Package Contents: 1 * USB Volume Controller 1 * data Cable 1 * 2.4G receiver Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.