Toughened (or tempered) glass is a type of safety glass that has increased strength and will usually shatter in small, square pieces when broken. It is used when strength, thermal resistance and safety are important considerations. Using toughened glass on automobile windshields would be a problem when a small stone hits the windshield at speed, as it would shatter into small squares endangering the driver and passengers. In commercial structures it is used in unframed assemblies such as frameless doors, structurally loaded applications and door lites and vision lites adjacent to doors. Toughened glass is typically four to six times the strength of annealed glass