Smart Lid vacuum seal containers keep food fresher 5x longer with just a press - vacuum seal to store food and liquids, lock out air and seal in freshness. Replace all your bulky storage containers and messy kitchen wraps. Store food or liquids, reheat, or keep food warm while entertaining. Made from ultra durable space-age polymers, lids are refrigerator, freezer, microwave and dishwasher safe. Use on glass, metal, ceramic or plastic bowl or dish of any shape or size. Use again and again! Set of four.