Built-in Bluetooth. After connecting to Bluetooth, make the calls on the phone directly. Answer the phone calls. Support hands-free calls Support advanced audio transmission mode Support the clock indicating while power is off High-quality digital stereo FM radio Support three-band radio store FM1-FM2-FM3, and can preset 18 radio stations. (Radio frequency: 87.5-108MHz) Support USB/TF card reader Support audio: MP3/WMA/WAV formats and so on Support folder play function Support remote control Rotary electronic volume control MP3 play supports pause /preview/repeat/random play and 10 tracks up/down selections Electronic type bass/treble/left and right balance/front and back balance volume control Front AUX audio input hole and rear terminal L / R audio RCA output hole 4-track high-power output (4 high-power loudspeakers) Work Voltage: 12V Clock Display In MP3 play status, short press CLK, the display will show "CLOCK" instead of MP3 information. The unit will turn to MP3 information if no operation within 5 seconds. The clock is a 24-hour clock. Clock Adjustment Short press the CLK to show the time. Long press the CLK and then rotate the knob to change the hour. Press again to change the minutes.