Review on Enhance Your Car Audio Experience with Bluetooth FM Transmitter: Wireless Radio Adapter, Hands-Free Calling, Dual USB Ports, TF Card/AUX Support by Chase Steele

Once paired with a bluetooth phone the fm transmitter has decent audio transmission considering the signal in your Phone starts and then transmits to the FM transmitter via Bluetooth, then the transmitter transmits the signal to your car's receiver. There is significant signal narrowing in the waveband, so tones are a bit muffled and the mids are heavy, with some high and low frequencies being lost. However, it does what it's designed to do with little fuss or confusion. PS, unlike other reviews, it automatically connects to smartphones. worth your money!