Bulletproof glass bulletproof glass is usually transparent material, such as polycarbonate thermoplastic (generally Lexan resin). It has the appearance and behavior of ordinary glass transmitted light, providing some protection against small arms firing. Bulletproof glass usually include polycarbonate layer is sandwiched among ordinary glass layer. Bullet looks easy breakdown of a layer of glass, but rugged polycarbonate layer will be before it can penetrate the inner layer of glass movement to stop bullets. Bulletproof glass is usually 70-75 mm thick. Historically, the bulletproof glass was glued together by a liquid rubber material made of glass. These chunks of bulletproof glass during World War II have been made public purposes, typically 100-120 mm thick and extremely heavy. For example, some banks unidirectional bulletproof glass bulletproof vehicle to promote the use of one-way bulletproof glass invention. This glass will resist lateral incoming small arms fire glass, but it will allow a shot at the opposite side of the glass (back side), such as those from the defensive side of the bulletproof car in shooting, which shot through the glass on the outside who threaten on. Bulletproof glass is usually made of a one-way story: brittle layer and layer on the inside of the flexible externally. When a bullet fired from outside, the bullet will first hit the fragile layer, and smashed a region. This will absorb some of the kinetic energy of the bullet, and a larger area of ??the spread of kinetic energy. When slowing down when the bullet hit a layer of flexible, it was blocked. However, when a bullet fired from the inside, it will first hit the flexible layer. Bullet flexible layer can breakdown because its energy is concentrated in a small area, a layer of brittle fracture when outwardly flexible spring outwardly that layer, and without prejudice to the bullet forward.