Some dude invented them years ago, basically a set of rings that you load a disposable piece of floss onto, making it way more comfortable but using way less plastic per use than floss picks.
I don't remember the exact details, but there was some kind of shenanigans where the big players in the existing dental products industry basically strong armed his suppliers out of working with him and he had to fold under a huge pile of debt or something.
If I recall it also had something to do with the regulations around the sanitary nature of floss, and how the stuff on the shelf now has basically none at all - it's just treated like regular string all the way through the production and distribution channels, and is never really kept particularly isolated from contaminants, but the ring refills were actually sanitary instead.
It sure does seem to be! Neato!