Those lead lined bags (at least the one I got) does not work. I fly weekly for work, and the last time I had 800 speed film in my camera I used the lead bag. The tsa guy operating the x-ray machine told me I had a 'bad lead bag--nice camera though'--he could see right thru it...so maybe it helps, but not totally. Also, I usually have 400 loaded, and this routinely goes thru multiple checks. I HAVE noticed fogging on 400 film that has gone thru multiple times...now I do an internet search for the location for a well stocked film store where I can get xp2 at my destination. Depending on how caotic it is at the screening, I may ask for a hand inspection, but the standard answer, is "oh, you don't need a hand inspection..." Air travel for me, has always been a PITA, but it is now a nightmare, at least it is if you have to fly 3 or 4 times a week...Definitely do not check any speed film, consider buying/developing on site, or carry-on 100/125 speed film...