When you are on a bike ride, you need to be aware of your surroundings and traffic.
This mirror mounts on your handlebar and provides a wide view of cars and other objects behind you, thanks to its convex shape. You can even pivot the mirror to reach any any view and fold it in when you are riding on a narrow trail.
At just three inches round, it is small and unobtrusive. Just pop off the plug at the end of your handlebar grip to install.
More details about the mirror: