Heat-resistant glass, Silicone. Maximum temperature differential: 120℃ / 248℉. Upper temperature tolerance: 140℃ / 284℉. Microwave and dishwasher safe. Use only for its intended purposes. Do not overheat in the microwave or heat without water. Do not overheat in a microwave as it may cause water to overflow. Remove the lid when heating in a microwave. After heating in a microwave, the container becomes very hot. Use mittens to hold. Wash with care. Do not use abrasive cleansers or steel wool. Sudden temperature change may break or shatter the product. While the glass is hot, do not pour cold liquids into it and do not place it on a wet cloth or a wet surface.