Volume control: Turn the knob to increase or decrease the volume. Track navigation: Previous track is achieved by doubleclicking the knob; Next track is achieved by a single click of the knob. Power operation: Turn the lever clockwise to turn on. Turn the lever counterclockwise to shut down. Audio sources and switching: Supports Bluetooth, TF card, FM, and AUX. To switch between sources, press the M key to cycle through the options. Compatibility and input options: Bluetooth for wireless playback, TF card for local playback, FM radio, and AUX input for wired connections. The M key provides quick source cycling for convenient use with multiple devices. Control and usability: The combination of a dedicated volume knob, a multi function knob for track control, and a power lever offers simple, one handed operation with clear tactile feedback. Source selection is integrated into a single M key for efficient navigation. Build and operation notes: The device uses an intuitive control layout with a knob and lever for easy access in various environments. It supports multiple audio sources to match different playback needs. Use scenarios In a car or vehicle setup: Use Bluetooth for wireless music playback or switch to FM or AUX as needed. Adjust volume with the knob without taking eyes off the road, navigate tracks with knob clicks, and power the unit on or off via the lever. At a desk or in a living space: Connect via Bluetooth or AUX to a phone, tablet, or computer. Use TF card playback for offline music, switch sources with the M key, and control volume directly from the device. On the go with portable use: Pair Bluetooth devices for hands listening where available, or play local TF card content. Cycle through sources quickly with the M key and manage playback with the knob and lever.