The acquired by me at Amazon bicycle rear view mirror can be easily and stably grow. The adjustment is also very good. Downside is unfortunately the quality of the mirror glass. In the convex curvature of the glass, for example, people are so greatly reduced in the real distance, that they are no longer to be defined exactly for the rearview mirror user. The structural change in the bend angle would indeed restrict the field of vision, but would be for the user an optical gain!