Just a tip: I broke several of these mounts just by handling the bike without the Edge mounted. If you locate the mount on your stem, then it's really easy to break off the tab if you grab the bike by the stem. In that configuration, the tab is very exposed; it just hangs off into space, and will snap off with very little upward deflection. With the Edge mounted, or if you mount it on the handlebars, then the tab is shielded somewhat.

So I finally learned to be careful about how I grab the stem so that my hand doesn't catch on the tab.