Just looking through the schedule and there's a Karin Brushmarker PRO programme on today. I don't do much colouring so wouldn't normally look but for some reason I did and was surprised to see in the details....
In case of air travel make sure the markers are tightly closed.
Do not use your Brushmarkers PRO during the flight.
It's been a while since I flew anywhere so I hadn't realised the restrictions were so specific these days.