I use an old fiberglass aerospace shipping container I salvaged from work many years ago. We used them to ship pay per view vcr tapes for the cable company I worked for. When vcr tapes became ancient history they just threw out the couple cases we still had laying around. It is o ring sealed to be air and water tight, has locking wing nut clamps, steel handles, aluminum reinforced, come with or without rollers, is nearly indestructable and even has a pressure release fitting on it. These things are available in all shapes and sizes. If you really need something heavy duty this is the way to go.
I'm a big fan of Pelican cases but these are in a whole different league.
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You have yourself a good find there!! I've been watching for those for years to protect our production equipment when on the road, either wildly expensive or unoptanium.