Lexan is GE's brand name for a type of plastic called "polycarbonate".  This plastic is virtually unbreakable.

From the Lexan product sheet:  "Lexan resin’s exceptional impact strength and practical toughness make parts virtually shatter-resistant, providing a high degree of safety and durability in service in the toughest of environments."

In layman's terms Lexan will not break if you hit it with a hammer.

It is clear, like glass.  SSI recommends Lexan to be inserted behind glass windows that are near doors.  The finished look is almost identical to the original.  Invisible security.

Lexan is a trademark of GE Plastics.
www.geplastics.com