wiki:
"
Pyrex (
trademarked as PYREX) is a
brand introduced by
Corning Inc. in 1908 for a line of clear, low-thermal-expansion
borosilicate glass used for
laboratory glassware and
kitchenware. Pyrex sold in the
United States is made of tempered
soda-lime 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.
World Kitchen, LLC, which was spun off from Corning in 1998, licensed the pyrex (all lower case) brand for their own line of kitchenware products—differentiated by their use of clear tempered soda-lime glass instead of borosilicate."
