I don’t know what I was thinking when I read your original comment, but I thought you meant the ones that come in the tubes. Guess I was half asleep. The extra tabs on the corners sound like they might be for structural support so that they don’t get crushed as much when shipping or so that the box they come in can be weaker. I know plenty of the ones with the basic glued design open up on their own when weight is put on it.