Helps reduce the glare of bright headlights from cars behind you. A car is fast approaching from the rear. Headlights begin to blind you. No worries. The Auto Day/Night Mirror automatically darkens to reduce the glare. Built-in compass makes using maps and following directions easier. Reduced glare reduces night time eye strain. Automatically adjusts for all light conditions- and perfectly replaces the standard mirror. Compass is included- which makes using maps and following directions even easier.