Lock&Lock borosilicate glass is unlike any other. Heat resistant and airtight (on select models with four locking system). It uses material that contains strong heat resistant properties which could withstand sudden change in temperature. Plastic lids are BPA free. Our heat-resistant glass is produced in temperatures above 2700°F which makes it harder to manufacture, but safer to use. LOCK&LOCK BOROSEAL thermal shock strength is 250°F. Our borosilicate glass can be used not only in a refrigerator, a microwave, and a dishwasher, but also in a 750°F conventional oven. Unlike normal or tempered glass, if Lock&Lock Boroseal gets broken by physical shock, it doesn"t break into numerous fragments and scatter. Therefore, it is safer and more suitable for you and your family. Cook in the oven with Lock&Lock glass or use it as bakeware (without lid). Microwave safe (without lid). It is salt and oxidation resistant and stain and odor resistant. Lock&Lock is so versatile you can go from oven to table at once and freezer to microwave at once. No more washing so many dirty dishes.