content: This is a great Bicycle Mirror, and if you ride in traffic an invaluable safety feature.Installation is easy but READ THE INSTRUCTIONS FIRST! The screws have a locking feature so they're VERY hard to turn. Use an appropriately sized screwdriver, installing the assembled unit as the LAST step in the process. Tighten the screws just tight enough so that the unit can be adjusted following installation, but not loose enough that bumps will 're-adjust' its position.