@sabbatical It's a spool from 620 film.

620 film was made between 1931-95. It was meant as an alternative for 120 film (made since 1901 and still made today) and the film itself was the same size. 120 film has a slightly larger spool made of plastic.

Since the film and the paper it's attached to is identical to 120, one can respool a fresh roll of from one spool to the other and that enables me to use my 1950's Brownie Hawkeye camera