Before I bought my Mirrycle MTB (same as the one described above), I had rigged a small, round wide angle mirror to my left glove using a pair of magnets. It worked great for several years and enabled me to easily and instantly adjust the mirror to any angle at any time. Eventually, people talked me out of it, convincing me that it was only a matter of time before I got distracted and accidentally steered, one-armed, into oncoming traffic. I'd imagine the mirror that connects to your arm is roughly the same concept?

Anyway, I'm really happy with the Mirrycle, and don't regret putting away my glove mirror at all.