Klein u. Good.

5.4 x 4.3 cm small. For fitness bike just right to retain a sporty touch. Since the mirror slightly enlarged the visibility is sufficient. By bungee wobbles or shakes the mirrors not on cobblestones.
The rubber may be a little more robust. Have a small rubber additionally fitted to protect. Adjustability is filigree (mm matter) but goes well. The only logical attachment is at Bar End, everything else will come to nothing. Adjusts the right thick Ergon Bar End's.
Without mirror you did not know what's behind a lot, now I see, at least if the road is clear.
So I can not recommend the purchase.
For 5 stars it is not enough to mount the rubber would be more stable. But for a well it was good enough.

Addendum: After 2 weeks use I increase to full marks and 5 stars.. This little thing has proved much better than expected. Rearward visibility is excellent. Absolutely no wobble or shake not even on poor road. Very good indeed.
Rad is upset and full of fallen on the mirror, nothing broken or damaged in the mirror. The mirror surface which supports the need to be very robust !!