I've used a FRIO for the last 6 years and never had an issue. As an example of my use. Last weekend I drove three hours, left my backpack with my FRIO in the car for 10 hours in 90 degree heat before getting to my hotel, no issues with my insulin. The FRIO itself felt a little warm on the outside but when I took the pen out and felt inside it was cool. Never had an issue with TSA and I fly probably 10 roundtrips a year.