See the wiki page for a list: https://en.wikipedia.org/wiki/Hidden_champions
(None of those examples are on that list.)
I thought I knew "International SOS", but I actually knew "SOS International", another entity altogether.
I'd heard of Bobcat, De La Rue, Embraer, McIlhenny, Petzl, Tandberg (famous for reel-to-reel tape-recorders). I do think it's wonderful that the list includes a company known for "wristwatch hands".
Molex is a pretty well-known name because of the eponymous connector, but I'd never considered whether it might be a company.
It has a revenue of R$20m, which falls within the arbirary hidden-champion revenue cut-off of US$5b only due to the poor BRL-USD exchange rate right now.