Patented Locking System: KENPOLY Containers Are Guaranteed Leak-proof (Airtight And Watertight) With Our Patented Four-hinge Locking System And Silicone Sealing Lid. This Assures you that whatever is inside is well protected and preserved. With these Klip lock container, you can easily prepare food for when you're on-the-go. Whether you're off to the gym, school or work, this set will keep your food fresher for longer. The air tight Klip lock feature ensures a secure seal. This versatile set is microwave, freezer and dishwasher safe making life that little bit easier.