The youtube video reviewing this isn’t very nice, it talks about how much of a pain it is to apply the special reflective tiny so the thing actually works, as well as a problem with things that look like they are appearing twice.
Here’s a better review of what appears to be this actual HUD unit:
I bought two of these the last time I saw them here. I installed mine following the directions, and the reflective surface falls off of the windshield regardless of what you do. The device itself requires an insane amount of tweaking just to get the speed to register properly (and that is just one function!). It is extremely small and is entirely not worth it.