Looking at the wider picture, security and screening of air cargo is coming under the spotlight in the US. Currently its a paper exercise, and the practicalities of checking cargo shipments are being reviewed. I am no expert in this area , but I'd have thought that there are practical difficulties to x-raying cargo shipments when they are housed in an aliminium uld. Xraying shipments in a plastic uld would not have the same problems. As ususal all imho, dyor.