decoweenie

I have flat mirror for signalling...

But for bubble checking or just general configuration checking while on deco, I use the cheap plastic round convex mirror sold at most hardware / supermarket store (with double end tape on the back) that you could stick on your car rearview mirror.

They come in 2" or 3" diameter, and great for seeing EVERYTHING.

If you are an instructor, you could use them to check on students when they are behind you (or your buddies). Or while scootering, videoing, etc. without having to stop and duck between your legs...