Pyrex (trademarked as PYREX) is a brand introduced by Corning Incorporated in 1915 for a line of clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware. Pyrex sold in the United States is now made of tempered glass, outside of North America the costlier borosilicate is still used.Corning no longer manufactures or markets Pyrex-branded borosilicate glass kitchenware and bakeware in the US, but Pyrex borosilicate products are still manufactured under license by various companies. World Kitchen, LLC, which was spun off from Corning in 1998, licensed the Pyrex brand for their own line of kitchenware products—differentiated by their use of clear tempered soda-lime glass instead of borosilicate.