1. Is this kind of marking safe? 2. Can't it be washed somehow away by thieves? 3. How can it be proved to insurance group that I have done the marking? 4.Is it mandatory to do rear-view mirror marking too?

​​1. Yes, the window marking is very safe.

2. It is impossible to remove the window marking because the registration number is etched into the glass.

3. I would keep the receipt to show that you have purchased the product and I would also take a couple of pictures, just to make sure.

4. The rear view mirror is not mandatory, no.