The storage containers made of oven-safe borosilicate glass have a silicone ring and are completely airtight and watertight. They are stackable, microwave, oven and freezer safe. Dishwasher safe. Leakproof seal that can be easily removed for thorough cleaning and 4 security snaps. The material from which the container is made is borosilicate glass, free of BPA. Durable and resistant to temperature changes. You can take it out of the freezer and put it in a preheated oven without worrying about damage. The containers can be stacked for easy storage. Can be used in the microwave and in the oven (after removing the lid). Can be washed in the dishwasher.