The glass sometimes cracks; it never shatters.
Window Armor, of Concord, is an after-market automotive product available through car dealerships for $495 to $695. Applied to the inside of automotive glass, the transparent film is so strong it is virtually impossible to break from the outside.
Some 98 percent of all smash-and-grabs are through side car windows. More importantly, the product keeps drivers and passengers safe from flying glass, the cause of 70 percent of injuries in side-impact collisions, the most common kind of automobile accident.
While the application to car windows is new, the technology is not.
"The government created this stuff from the point of view of protecting against bullets, bombs, bats, bricks," Warner said.
Security laminate film, essentially tightly woven polyester, has reinforced the windows of government buildings for nearly 20 years.
The idea for Window Armor grew out of conversations with New York car dealers.
The challenge was to find a way to stick the film efficiently to the slightly curved windows of cars.
"The breakthrough really came last spring," Warner said. "Finally the application process was absolutely repeatable."