Containers come in many different types, and in a few different sizes. There are flat racks, tank containers, open top containers, and of course the standard shipping container. The length of the containers is always 20' or 40', and the width is always the same at 8'. Many many companies are involved in this business, for example:
Attached to this listing you can find a handful of photos of shipping containers. These containers are traveling around the world all the time. Using the unique container number the shipping lines, container lease companies and port operators can keep track of each individual box: where it is, and where it has to go.
And now to you geocacher the task to find your destination. The cache is not a shipping container, it's just a small plastic jar. Minor scrambling including scaling a fence is needed to get to the cache. Good luck!
The 4* difficulty is for the puzzle; the cache itself should be easy to find, 1-2* difficulty. Good luck!