These kit cars came out in the 90s. They are resin with brass details. Hensons (now "Trains Emporium") produced these in very limited numbers and has no plans to re-run them (in fact, they don't even know where the molds are anymore).
I'm told that this particular car is actually a model of a cryogenic tank car. The prototype is UTLX 80011, a 15,000 gallon liquid air tank car built 12/60. The model does have a few more boxes and other detailing along the top, but it's basically the same car. An article about said car appears in the Oct, 1963 issue of Model Railroader magazine.
Cryogenic tank cars are estimated to make up less than 1% of the tank car fleet in North America, with perhaps fewer than 200 actually in service. They operate with a pressure range of 0 to 25psi. They have capacities that range from about 16,000 gallons to 30,000 gallons. They are generally white in color, and have a variety of valves, fittings and inlets/outlets, and gauging devices on the sides or ends. They transport cryogenic products (minus 130 degrees F or below), all of which fall into the hazardous material classification.
Sorry about the picture. If you have a better one, do please send it to me.