1. Stops fog
Stops fog and eliminates the need for carrying a tinted visor.
When I head to work, it is warm and sunny, but on the way home it is dark, and usually pretty chilly so my lens tends to fog up. With the clear insert, the lens darkens up enough when the sun hits it that I don't need to swap visors or use sunglasses. Once the sun goes down, the tint fades and I can see clearly after dark as well. Also does a great job of stopping the fog.
