Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Would this work to play through the radio/car speakers? Or does it just charge it and allow you to play the music from the MP3 player's speakers?
Document: For what it is I'd say it's worth checking it out if you're not looking to spend a lot of cash in your older car for a new stereo but still want to play you MP3 player over the speakers. The hardest part is finding a dead channel to broadcast it on since radio is so saturated now.
This is a great way to play music with a mp3 player or phone in you car if you don't have a radio that supports a mp3 player. Make sure you tune your radio to a no broadcast station to hear your music otherwise it wont work/ didn't work for me in my truck. This adapter worked with my old zune mp3 player from 2008 /2009 w/o a problem in case anyone is wondering if they need a app to use it.
I think it fits the bill perfectly. It does exactly as it describes. It transfer music or recordings from your mps player, ipad, phone, etc. to your car speakers. Pick a channel that works and out comes the sound. Easy to use with little to no set up. Perfect for those of us that have a car in the collection that pre-dates MP3 audio insert on the dashboard.
I wanted to listen to eBooks through my car stereo speakers. This allows me to do that. My phone does read the transmitter as a headset rather than headphone, so I needed to install an app to keep the phone from making random calls and skipping chapters, but once I figured that out, I could read happily with my ears in the car! It may not work as well for listening to music if you need super high quality, but it works well for my purposes.
There isn't anything on the radio but commercials. With this I can listen to my music from Spotify. You have to make sure to link up the station to the digital read out in order for it to work. Play around with the stations to find a nonstatic frequency. Really enjoying it.
I thought this was an ok product at first. It had a good range of stations to choose from, so no matter where you are, you could find a useable station. I did find that this product would occasionally cause an annoying buzzing or humming sound to emit through the car speakers while the music was playing and while no music was playing. I could usually unplug it and plug it back in to fix it, though.
It must have arrived DoA or something, because it just straight up didn't work. I tried it with my phone, with my MP3 player and got nothing but a very quiet hum through the channel where there was supposed to be music.
Pros:The signal is strong and reliable.I like the USB charger built in, allowing you to charge your device at the same time.Con:The signal shuts off if no music is being sent from the mp3 player for 30-60 seconds. This is quite annoying - you pause your music to take a call, then after 30-60 seconds the transmitter shuts off leaving you with loud static/interference blaring from the speakers.
I have a 2003 Honda Accord & it does not have the luxury of having a auxiliary jack available in the stereo dash. So after purchasing different FM transmitters I finally ran across one that not only plugs into my iPod, it also plugs into my smartphone! Find a free radio station, plug into your MP3 player of choice, cruise and jam! Simple & plain. It also has a USB port to charge your device but you must supply your own cable.
I have a friend who has a similar product and he showed it to me and I thought that was cool beings I have a older car that doesn't have that .Hooked it up and works GREAT and also you can get phone calls though your car speakers which is quite helpful with the Laws in my State you can't use a cell while driving and it solves that problem. I would recommend this product to anyone THANX AMAZON : ) !! Very Happy
Answer: You tune it to an unused radio frequency, and the music on your device plays through the car speakers.