Key benefits Flexible audio sources: Bluetooth, TF card, FM radio, and AUX input provide multiple playback options from a single device. Simple source switching: Press the M key to cycle through available audio sources, making it easy to choose the right mode without fumbling for cables or remotes. Intuitive playback control: Previous track is triggered by doubleclicking the knob; Next track by a single click, enabling quick navigation while keeping your eyes on the road or task at hand. Easy volume control: Turn the knob to increase or decrease volume with precise, tactile feedback. Straightforward power operation: Turn the lever clockwise to turn on; turn the lever counterclockwise to shut down. What you get Audio source options: Bluetooth, TF card, FM, AUX Mechanical controls: M key for source selection, knob for play/ pause navigation and volume, lever for power How it works Audio sources Bluetooth: wireless streaming from compatible devices TF card: local playback from microSD card FM: traditional radio reception AUX: wired connection to external devices Source switching Press the M key to cycle through Bluetooth, TF card, FM, and AUX Playback control Previous track: doubleclick the knob Next track: singleclick the knob Volume: turn the knob to adjust Power On: rotate the lever clockwise Off: rotate the lever counterclockwise to 23 practical use scenarios In a vehicle Use as a central media controller for music from your phone via Bluetooth, stored files on a TF card, local FM radio, or external media through AUX. Switch sources with the M key, change tracks with the knob, and adjust volume on the fly without taking your eyes off the road. At home or in an office Connect to a speaker system via AUX or Bluetooth for flexible playback. Keep a TF card loaded with your playlists for uninterrupted listening, or switch to FM radio when you want quick access to local stations. Outdoors or in a workshop Use Bluetooth or TF card playback for background music or instructional audio. The knobbased control lets you navigate tracks and adjust volume while keeping your hands for tasks. Compatibility and performance notes Supports Bluetooth devices for wireless audio Accepts TF cards for local playback Includes FM radio functionality AUX input for wired connections Control is via a tactile knob and lever for reliable invehicle or stationary use This description preserves the original product functions and control methods while presenting clear, customerfriendly language and practical usage guidance.