Jenaer Glass is the foremost maker of heat-proof glass. All Jenaer glass teapots, egg coddlers, bowls and casseroles can withstand temperatures of up to 450 degrees Celsius or 842 degrees Fahrenheit. Withstanding such temperatures allows Jenaer Glass to be used in the oven or microwave easily. Jenaer Glass is very durable and can handle fluctuating temperature changes. The borosilicate glass used in Jenaer Glass adds other perks to using this glass. It is dishwasher safe, easy to clean, neutral in flavor, is totally pure and will not throw off components of its construction or gasses. This glass is the ideal glass for any allergy sufferer.