This is a special purpose tank car owned by the United States Navy for transporting helium gas.
Long term model railroaders will recognize this car as one of the Ambroid Companys 1 of 5000 kits circa 1960.
It has several unusual features:
1. It does not have a roof.
2. It has two completely separate AB brake systems (one serving each bogey).
3. The 30 tanks are refrigerated to a very low temperature.