Why does anyone think they don't flash. Just like any other film camers a Truvello needs illumination to guarentee a good picture.
The difference between a Gatso and a Truvello is that the Gatso uses Radar and the Truvello doesn't.
Mainly because it says "no flash" and "infrared flash which is not visible to driver" on their manufacturers website and every other information found on the web about them
Another bit of nastiness is that you don't have to receive it at all for it to be valid. If it gets lost in the post it doesn't make any difference, as long as they post it to the registered keeper within 14 days you're done