Stadium seat dimensions

I'm going to a football game at Austin this season. I've looked up the requirements for bringing in stadium seats and it says 12x12x18. Does this mean when folded, or unfolded? If it means unfolded I'm having a really hard time finding something that fits those requirements.

I would just get the stadium seats they have there, but last time I did that they were crazy uncomfortable.

If you have one that works and that has been allowed inside, I would love a link.

Any help would be appreciated!