I brought this item as the photos on the web site showed the item fitted with metal tab towards the outer edge. I am not sure what the tab does exactly. It helps to locate the mirror when fitting and probably acts as a damper to prevent the mirror vibrating while driving. The unit did not have the tab fitted to the mirror, but I was able to prise the metal tab from original mirror and install it on the new mirror.
Also, the original mirror had a convex area at the outer edge of the mirror (shown in the web photos too). The JCar part does not have this special outer convex area, but rather has a slight overall convex shape to improve field of vision.