Heat-resistant glass is a type of glass that can withstand high temperatures without breaking or melting. It is commonly used in laboratories and industrial applications. Two of the most popular brands of heat-resistant glass are Silex and Pyrex. Silex is a brand of borosilicate glass, which is composed of silica and boron trioxide. Pyrex is a brand of borosilicate glass made by Corning Incorporated. Both types of glass are highly resistant to thermal shock and can withstand temperatures up to 500°C.