The BT Car FM Transmitter is a multifunctional device that lets you enjoy your favorite music, answer calls, and charge your devices in your car. With this transmitter, you can turn your car stereo into Bluetooth and play music from your cell phone, a USB flash drive, or a microSD card Bluetooth 5.0: a technology that guarantees a fast, stable, and energy-efficient connection with your compatible devices FM transmission: a system that allows you to tune into the frequency of your car stereo and listen to music or calls on your car speakers Hands-free: a built-in microphone and an answer button allow you to answer and hang up calls with a single touch, without distracting yourself from the road MP3 player: a USB port and a microSD slot that allow you to play music files in MP3 or WMA format, with a maximum capacity of 32 GB USB Charger: Two USB ports allow you to charge two devices at the same time, with a total output of 3.1A LED Display: A screen that shows you the transmission frequency, track number, battery voltage, and playing mode