I have never used a mirror, but decided maybe it's time I tried one out in conjunction with my Garmin Varia. Gonna try out two options: A Zefal Spy that seems to have a lot of location options; also ordered a Clearview Micro Helmet Mirror. I liked the smaller form factor of the Clearview vs other helmet mirrors. The Clearview hasn't come in yet so I can't say much about it function-wise, but it gets good reviews.