Captn SE is right. I have recently traveled with my EXII. I went to the local post office store and purchased a box that meet airline size restrictions...if I remember it was something like 10x16x24 inches, but I would recommend you check online with the airline that you are using. I think if you have your original box that the SE came in, that would most likely work great, but I didn't have my original box handy.
On my return trip home I was in a hurry and wasn't thinking...I ended up packing my digging tools in the carry on box with my detector...WOW, that was a mistake...security didn't like that one at all, seeing the Lesche, Raptor and small gator diggers in there. In the end I had to end up checking the box and it cost me another $50. That is mistake I will never make again.
The key is to pack your digging equipment in the suitcase you are checking in...not the carry on. Plus another heads up, my cousin had some problems with security not liking the mass amount of coins he had in his carry on. It was all of his finds from that trip in a large freezer baggie. I believe they still let him on with it, but it might not be a bad idea to toss that in your check suitcase either. I did that with all my clad, but my silver coins I brought on the plane with me. Security didn't have a problem with it.