Upon receiving the ViewPoint mirror, my first impression was that there was no way that this tiny mirror would do what CycleAware claimed.
I have to say that I was pleasantly surprised. After experimenting for a while I found that the best way to mount this mirror to my sunglasses was to mount the high side of the mounting base facing right & turned slightly counter clockwise so that the high side is facing in about the 2 o'clock position. I mounted it about 1/2 way up on the left lens & about 1/8" from the edge of the sunglass frame. This enables me to clearly see any traffic to my left.
It's a bit tricky dealing with the small sticky pads that come with the mirror. By the time that I finally got it positioned exactly where I wanted the sticky pad was hardly holding the mirror to the lens because of my handling it. There was no way that I would feel comfortable leaving it attached with the first pad. If this mirror falls off while you are riding, it would be like finding a needle in a haystack. It is sooo tiny. They do give you a spare but I found that I was able to make my own using double sided tape that was not too thick & with a paper punch I made as many sticky pads as I wanted and they seem to work just fine.
I find that it is an excellent product & I highly recommend it.