I carried one of these cases as camera carry on luggage on a plane from Sydney to Brisbane. Halfway home I opened it up, it fairly popped open. I wasn't thinking. Then when I got home and tried to open it again I couldn't budge it. I was seriously thinking of getting out a pinch bar to lever it open.
Then I noticed the vent.
They have quite a good air seal.
BTW mine are labelled "Kinchrome"