Bluetooth 5.3 for stable connection and clear sound - Advanced Bluetooth 5.3 delivers a reliable, low latency connection with noise reduction for crystal clear hands-free calls. Automatically connects to your smartphone, making it perfect for cars without built in Bluetooth. Dual USB fast charging 5V/3.1A with safety protection - Two USB ports provide up to 3.1A total charging for two devices at the same time. Built in protections guard against overvoltage, overheating and short circuits. Includes a USB-C adapter for maximum compatibility. 3 in 1 music playback: Bluetooth, USB & Micro SD/TF - Play music via Bluetooth, USB stick or Micro SD/TF card. Ideal for older car stereos without Bluetooth. The FM transmitter sends audio to a free FM frequency with high quality stereo sound. Built in microphone and one button control - Hands free calling at the touch of a button. The built in microphone features echo cancellation for clear communication. The multi function button lets you answer or end calls, control music and adjust volume. Use scenarios - In a non Bluetooth car, connect your phone by Bluetooth and stream music while making hands free calls. - On road trips, play music from USB or Micro SD/TF card and charge two devices simultaneously. - In rental or shared cars, quickly upgrade the audio system with Bluetooth streaming and hands free calls.