It's kinda like saying something is "Mil-SPEC". What does that mean?
I worked in a private company that did lot/most of its work for US Gov customers and you get used to those claims and others similar in nature. Since my final job before retiring was running a qualification review board of completed systems/subsystems for aerospace payloads i am especially sensitive when performing the final review to include extensive audits of parts, materials and processes to the point of on-site surveillance and complete parts audits. It is outrageously expensive but necessary when ultimately installed in something that will be beyond repair once in orbit.
I don't need or want that in my nanovna and can usually do my own verification/validations to the extent required.
I like the Al case, but as somebody mentioned, it likely doesn't justify doubling the price.
When will affordable metal 3D printers be available?
I guess there are work-arounds for EMI shielding that accomplish what we need.
2sheds