The Pebbly storage boxes are made of borosilicate glass. This material has numerous good qualities. Firstly, this glass is highly resistant to temperature changes. You can take your storage box out of the refrigerator and place it directly into a hot oven without fear. It can withstand temperatures up to 400° C, and thermal shocks (instantaneous changes in temperature) of 180°C. Borosilicate glass is also safer for culinary use, because if it does break it will crack, and not explode. It does not stain and will not retain odors. These qualities make Pebbly storage boxes highly compatible with the oven, microwave, refrigerator or freezer. The boxes are hygienic, airtight and certified BPA free. Additionally, they are easy to clean: the glass is dishwasher friendly, however we recommend washing the lid by hand to prevent it from deforming when in contact with heat.