Note that the type I'm looking for are NOT lever-arm, ring binders: they generally screw together, or in the later version, have a quick-release sliding catch. The type I'm looking for also has substantial, thick hard covers, which the earlier T.O./USAAF/USAF type often do too. They are always of the 'post-type' (rather than ring) binding and thus far I've only ever seen them used for military manuals.
I think I am looking at a commercial supplier rather than a retail type of item. See mine and MiTasol's photos if anyone can help.