The Safe Zone Bicycle Helmet Mirror is the highest-quality helmet-mounted bicycle mirror on the market. The 2.25" mirror yields an extremely wide field of view, much larger than any other helmet mirror.  The arm is easy to adjust, maintains functionality and is guaranteed not to loosen over time. Simply attach the mirror base to the helmet with the included straps, straighten the mirror arm, and snap the mirror directly into the base to install. Once it's installed, peel off the plastic film protecting the mirror. For any mounting difficulties please view the detailed photos and videos on the Safe Zone Installation tab on efficientvelo.com. The Safe Zone Mirror will fit nearly all helmets. Please note the Safe Zone ships with a protective plastic film over mirror which must be removed before first use. Once you have the mirror mounted on your helmet, we recommend doing all major adjustments when you're not riding.