I received this the other day and have been testing it in the back of my car. I have set up a few of my own messages to communicate with other drivers, which I do from my smartphone which is mounted on a phone holder. The device is bright and easy to read, even in daylight, although it's best to ensure it's at an angle where it's pointing directly at the intended recipient - if you have it at an angle, like on a windscreen or sloped rear window, it's a little harder to read in daylight. It's plenty big enough too. Very easy to install using the provided double sided tape, or you can just do what I did and stick the gummy surface of the LED board directly to the window.The app which controls it is the only downside - it's a bit bloated and unnecessarily complex, but this is hopefully something which can be changed with a future software update.Overall a very good device and if you need something like this, I wouldn't hesitate to buy one!