These are surplus US Military cases which were originally used to store and transport hydraulic pumps.
The outside is an air and watertight hard plastic case with six latches, two handles, and a pressure release valve. The outside measurements are about 17" X 17" X 13", a one gallon paint can was shown in one of the photos as a visual size reference.
Inside is soft foam that you could remove or carve to fit the item you wish to use it for.
With multiple units they are indexed to stack nicely together, I have had them as many as eight high and are very well built, better than the famous Pelican brand IMO. They are easily strong enough to stand on.
$40 each or two for $70.
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