Tempered glass is relied in many applications where safety is a key concern. Some of these applications include vehicle passenger windows, rear windshields, phone booths, guard booth windows, patio furniture, decorative railing glass, basketball hoop backboards, racket ball court glass, and more. Not only is tempered glass four to six times stronger than annealed glass, but if it does break, it will fracture into small, less dangerous pieces while annealed glass has a tendency to shatter into large jagged shards. There two ways to temper glass: thermal tempering and chemical tempering. Thermal tempering uses an oven to heat the glass (usually to around 6200º Celsius) and then cooled quickly with evenly spaced high pressure blowers. This fast cooling causes high surface compression. The chemical tempering process, on the other hand, combines heat and a molten potassium salt bath, which causes atoms to exchanges places, making the chemical structure of the glass more crowded and thus, compressed. The compressed state, rather than high tension state, is what offers the desired strength of the glass.