It’s called “Pullman” because it’s a canned ham that is packed in long tins called “Pullman cans” because they are shaped like railway cars in a long rectangle.
The weight of the ham will be between 4 to 16 pounds (1 3/4 to 7 1/4 kg.) The size will be either 4 inches tall by 4 inches wide (10 by 10 cm), or 4 inches wide by 10 inches tall (10 by 25 cm.) The length can vary from 8 inches to 20 inches (20 to 50 cm.)
The US Army and US Air Force specify that they want theirs in 4 by 6 inch (10 to 15 cm) rectangles, weighing between 10 and 15 pounds (4 1/2 to 7 kg.) [1]
Instead of being shipped in tins, it may be sealed in tough plastic packaging.
It is used for slicing for sandwiches, or for dicing for cooking. It is very easy to slice for sandwiches, especially for institutions to machine slice.
A good deal of it is made abroad in countries such as Denmark.
Sources
[1] US AIR Force Food Specifications (June 2004) Item code 113012