Simultaneous Connection of Dual --- If you have two mobile phones, the Bluetooth FM Transmitter supports the simultaneous connection of two mobile phones, the first mobile phone that is successfully connected is played by default, but when the mobile phone calls, it will automatically switch to the incoming mobile phone Handsfree Bluetooth --- Connect cellphone and this Bluetooth adapter via Bluetooth, One-click the button to answer/redial/hang up or reject calls. Built-in microphones and noise suppression (CVC) tech for clearer Hands-Free Call. You can keep your eyes on the road making your driving more interesting and safe Crystal Clear Music Streaming --- You can stream music on your car stereo via Bluetooth/ USB Flash Drive (32GB) / microSD Card (32GB). Advanced noise reduction technology will ensure quality, crystal clear sound. Support WMA MP3 WAV APE FLAC music formats in USB flash drive or microSD card; Also, with the wider range from 88.1MHz - 107.9 MHz, you can get more stable music experience Hi-Fi Stereo Music Streaming --- The FM Transmitter Bluetooth 5.0 with DSP technology could deliver 2x steadier transmission speed without distortion for Hi-Fi stereo music LED Voltmeter Display --- The FM transmitter will display car's voltage when plugged into the cigarette lighter. Keep abreast of car battery health at all times to avoid problems when driving