I like to play around with old Graflex SLRs. There were rollfilm backs for these in sizes to match these cameras. For instance, a 2 1/4 x 3 1/4 camera would have taken Type 50 film. My 3 1/4 x 4 1/4 Graflex takes Type 51 film. It is interesting to note that the inside of the back is labeled:

4 1/4 x 3 1/4
GRAFLEX ROLL HOLDER
1922 MODEL
TAKES
No 51 EASTMAN GRAFLEX FILM

There is a patent date of June 20, 1915. There are two empty film rolls inside with wooden cores and metal ends. I believe that this type of film was discontinued in the 1940's.
Dave