I use a Third Eye bar end mirror. Holds its position when adjusted, and no vibration problems.

After an incident last week I'm considering getting one for the right side as well...some crazy guy in a white Ford Ranger blew by on the dirt shoulder to pass the 18 wheeler that was following me in the 2 lane 55mph section I ride on (the shoulder isn't safe to ride on, let alone drive on). I had to swerve left towards the center line to avoid a collision with the Ranger as he cut off the tractor/trailer. Luckily I heard it coming. Next time I'd like to see it coming too.