FREEZER AND MICROWAVE SAFE – These round food containers are incredibly stable and durable thanks to their robust design and construction. Both freezable and microwaveable they can to withstand temperatures from -20C to +110C (-4F - 230F) It is not recommended for use in a microwave with a wattage output of higher than 800 Watts. A microwave set higher than 800 watt may damage the container.