Originally Posted by Lazy Dog

You might want to approach Gentex Optics out of Connecticut. They are one of the world's largest suppliers of Lexan optical products and specialize in shields like this.

For questions about Transitions Vantage lenses, http://www.transitionsvantage.com/ is a good place to start. They seem to darken in about 1.5 minutes in cooler temperatures (60-70 degrees).