This is from a few years ago, the Sakura series. I mainly used it in the office to hold hot water, pouring it into paper cups. As you can see in the photos, there are scratches and water stains inside. If you're concerned, they may come off with citric acid or baking soda. The lid opens and closes, the rubber gasket, and the lock all function without issue. I don't think it was advertised as completely airtight, but it didn't leak even when placed sideways in a bag. Since it's a Thermos, it might have cold and heat retention properties.