This thing is rather amazing. It basically sucked out all air from the plastic bag. In this video my wife and I were sealing 10 cups of rice into a cheap plastic. As you can see here, it manage to suck all air out from the bag that eventually the package itself become harden (you can even knock on it).
I'm sure the rice can easily last for many years this way.
(Yes, that was my wife's voice you've heard in the early part of the clip. I was telling her not to let her voice be heard but it was too late. The drumming noise at the background is my two daughters on the first floor playing).
(At first, the video wasn't that bad when I upload it to Youtube. But after allowing Youtube to 'stabilize' the video it's end up getting worse. But at least you can still view it)