Joyroom Bluetooth 5.0 FM Transmitter USB Aux Modulator Handsfree Car Audio MP3 Player 3.1A Fast Charge Dual USB Car Charger 1. 3.1a quick charging, super quick charging, general use of android and apple, compatible with mainstream 12-24v models 2. Bluetooth hands-free call, one-button operation, carefree driving;Navigation voice broadcast, more accurate 3. Compatible with a variety of brand U disk, TF card, plug and play 4. Upgrade smart bluetooth 5.0, full car 360° stereo surround 5. Lossless audio decoding, high resolution, high performance stereo, no jam, more shocking sound quality 6. Digital display screen, real-time monitoring of battery voltage, obvious abnormal voltage 7. Six protection functions, support over current, over voltage, over power, under voltage, over temperature, short circuit protection, safer use