Food Grade Material: These stretch lids are made from food grade silicone, safe and healthy, they can directly touch the food, non-toxic and odorless, worry-free. Microwave & Freezer Safe: The temperature range of the expandable silicone lids is -70C to 230C, safe for the microwave, freezer, and oven. Stretchy and durable: Thanks to the silicone material, these lids can be extended to fit the containers. They are also easy to clean, durable, and reusable. Tight Seal: With excellent sealing, it helps keep fruits, vegetables, drinks, and other food scraps fresh. Waste less food while saving money. Also, avoid mixing smells, to keep your refrigerator looking fresh at all times. Set of 12 and 6 sizes: Expandable silicone lids are available in a variety of sizes.