GlassLock containers let you store, re-heat and transport leftovers or lunches without worrying about chemicals leaching into your food. The containers themselves are made of rugged tempered glass, impervious to interaction with anything you eat. The BPA-free plastic lids feature air-and-water-tight silicone seals, so you can transport whatever you like, even liquids or soups, without worrying about a spill or leak. Each GlassLock container has four hinged latches that snap down to lock the lid in place, hermitcally sealing the food inside. These things seal tight! The design of the lids allows for stable stacking of GlassLock containers in the refrigerator. GlassLock containers are safe in the freezer, the microwave, and the dishwasher. What's not to like?