Stainless steel products are not allowed to be used in the microwave. They are also not designed to be used in the oven or on the grill as the material becomes extremely hot and there is a risk of being burned. The containers can basically be used for freezing. However, we do not recommend it as frequent freezing can lead to material fatigue. This shortens the lifetime of the boxes. In addition, you should take care not to fill the frozen food too high so that the frozen food can spread without stretching the container. The frozen product can cause a very high pressure and deform the container significantly.