I have purchased them not long ago, great product!
If you perform BOTH techniques, whilst NOT tailgating obviously (only a fool breaks the two second rule), and keep constant awareness of the vehicles around you you'll find you'll be safer on the road ;)
Yes it is frightening to know there are drivers turn their head around to look over their shoulders, doing so sounds very much like the opening of a car crash. Mirrors work WAY better than not keeping drivers look forward all the time.
These are great for babies who are trying to watch CBeebies on their tablets and don't want any sun glare...
Yeah, whatever. You win.