An FM transmitter is designed to connect your smartphone or portable audio device to the speaker system in your car or truck, allowing you to stream music even if you have an older vehicle. It works by creating its own FM radio signal. Your car can then pick up the signal and play your music or podcast from the truck or car speakers just like it would a radio station.

To connect your phone to an FM adapter, simply plug it in with a phone cable that ends in a compatible USB. For power, many FM transmitters plug into your vehicle’s 12-volt accessories socket—also called the cigarette lighter—but some use independent batteries so they can be placed anywhere.

If you don’t want to put out the money to update your car’s audio system, a Bluetooth FM transmitter is a great workaround for older cars that are not outfitted to connect with smartphones.

The basic Bluetooth radio transmitter for car use will include the port for your phone’s cable and a way to set the station you want to transmit to your car. As mentioned, most FM adapters plug into your 12-volt outlet, but you can find models that double as a phone mount for your car.

Having a car phone mount is important for keeping your phone in a convenient place while you are driving. If you don’t have vehicle GPS, a well-positioned phone mount can allow you to see the GPS directions on your smartphone without taking your eyes off the road.

Many FM transmitters also double as car chargers, so they can keep your device from running out of battery while you’re on the road. Adding an FM adapter to the collection of useful gadgets for your car means you can tick off multiple categories at once!