Just opened a box I bought over the winter. Not a biggy but it has a nice thick plastic inside. These boxes are NOT triple boxes so don't expect it.
I'm going to take them out and put them in a Bergger 8x10 box that is triple boxed.
I've never had a problem with loose sheets in a triple box before. I used to walk around Manhattan in the old days with boxes of exposed film inside a triple box with no plastic.