Virtual Glass is a Taelon technology. It is an energy field that takes the place of traditional glass. It is used in Taelon Shuttles and many Taelon buildings such as the Federal Building where William Boone's office is. Virtual glass halts anything that tries to move through it at anything fast than human walking speed (the precise speed could probably be customized). As Nell Hagar discovered when she ran into a Virtual Glass window in Boone's office, the energy field can cause a Human to be momentarily stunned ("Sandoval's Run").