Never having looked up their placement, proper or otherwise, I believe all of mine have been on the bottom of the Leica cassette, on whatever type I’ve used.
i believe they are ment to be a lifter of the raw film instead of using a spring to position the interior oversized cassette, though I’m not sure, only knowing they have have come batches of cassettes bought from different folks.
They are also a bit thick and of black wool.
It might be they supposed to fit on the outside of the bottom of the cassette, instead of a lifting spring, such as I used on my IIIC, when I had one.
As a piece of quality kit, I’m still glad to have them and still hope to find a Ten Dollar Leica one day that’ll use them; part of the romance of the Leica Barnack or ‘M’.