The lid works well on smooth rims of stainless steel, glass, plastic and melamine for example. We've also used it on glazed stoneware with good results . Seals tight Prevents spills - the lid creates a seal for reheating and storing Reusable - Can be used again and again Fun and attention getting! Locks in moisture while storing or cooking Made with BPA-free, food-grade silicone that is: Oven safe to 428F Freezer safe to -40F Microwave Safe Dishwasher Safe