Feature: 1.3 playing modes: This FM transmitter supports 3 playing sources: Bluetooth, TF card, USB flash drive. 2.Crystal sound effect: This FM transmitter utilizes the most advanced interference and noise cancellation technology, which provides crystal sound quality and more stable signal. 3.Other functions: Built-in microphone feature supports hands-free talking; support TF/Micro SD Card in FAT format up to 32G; support A2DP; support MP3/WMA format; support AUX output and input. 4.Easy to use: Easy pairing with Bluetooth stereo headset, headphones, speakers and other Bluetooth stereo audio enabled system. It will pair automatically after you power on. .