What the heck? They don’t even mention the company’s name? Who is it? Safecastle maybe?
We have a 20’x40’ custom-version of the Shipping Container model on our 200ac Family Farm. Dad & I built/installed it 12ft underground.
http://www.atlassurvivalshelters.com/aboutus/nbc/
This is the best-built unit on the market and can be customized very easily, to whatever config a person wants to do with it.