We have a laptop whose speakers have very low volume. Additionally, we have an old good stereo that has absolutely no audio input. Therefore, in our case, this device was the best and most economical solution in order to listen to the laptop's sound through the stereo speakers.
The device does its job very well as long as you find a frequency that doesn't "catch" any station. We live in the Athens area and the frequency 96.0 is completely empty (we had trouble finding one). At this frequency, the device transmits the sound of the laptop without any interference and with very good quality (video and music from YouTube, etc.).
In terms of battery life, its quality is laughable. However, the problem was easily solved as we constantly have it connected to a nearby USB port.
Also, regarding the build quality, the device is quite "fake". But given its low cost and the fact that it performs its intended job flawlessly, this issue is surpassed.

The battery drains quickly, so it's good to have a power source with you.
The car radio I used it on could only play stations with a good signal, so it was very easy to find an empty station and use it to transmit myself. The quality was very good.
The secret is not to put volume on the device that sends the signal, but on the one that receives it (car, home stereo, etc.).

Lost money and shipping etc... Stay away guys, it's the worst. Supposedly it has a rechargeable battery, but if it's not connected to a power source to charge, it's completely useless, and even when powered, it still has parasites. In a BMW E46 with a factory sound system, it's a total disappointment.

In order to have a long range, you need to have it connected to the USB. Simply put, it acts as an antenna! In an open space, with the laptop on the balcony, I can easily play music and it reaches a comfortable distance of 50 meters.

Trying it at various frequencies on the radio, I didn't find any where there weren't a few parasites heard.