The Xiaomi Roidmi is a car charger and Bluetooth FM transmitter. That means that it can wirelessly transmit audio from your phone to your car stereo. It's also a 2-port USB charger, so you can charge your phone while you drive, and even better, it's got a 2.1A port for faster charging. This is great for people like me -- my car stereo doesn't have an aux port, and it would cost over $300 to install a new stereo! Instead, I spent $10 on the Xiaomi Roidmi and it's great!