Thanks rsteinmetz70112. I understand the rules and the concept of the box, I just wondered if anyone had ever actually measured the box to see if they are accurate or if they have added more space and just not advertised it.

When I'm at the airport I will just have to measure the box!

Although I read a lot of comments saying they rarely check the size, I also wanted to bring a wheeled bag and I have read comments saying wheeled bags as a Personal Item often get challenged.