I found this see through Single 8 film cartridge in a Fijifilm Z800 I bought at a local car boot sale.
Why is it "See Through"? It's got FUJI FILM branded black tape with a length of film in it too.
I have been looking for a re loadable single 8 film cartridge.
It could be a demonstration cart for promotional stuff, just saying. it would not work as light would ruin the film unless loaded into the camera in total darkness (which would not be difficult )