For Anthony Marsh- Kodak Double-X (real name Eastman Double-X or Eastman 5222) motion picture stock with a daylight rating of ISO 250 and ISO 200 for tungsten. Eastman Kodak markets films for still camera market as Kodak and motion picture as Eastman. This is a different film than the Kodak Super XX that was replaced by Tri-X for roll film and 35mm sizes in 1954. It remained available in sheet film into the 90's as it was useful in making color separation negatives before newspapers used computer technology to publish color photos. Three exposures through primary color filters were made on this film and it required pinpoint registration during printing. During the the 50's, 60's, and 70's a popular way to economize with 35mm shooting was to buy short ends (left over motion picture film) and reload it into standard cassettes. Even today it is done, but short ends are hard to find now. In the early 2000's is was buying Eastman Double-X for 5 cents a foot, which was quite a bargain. In recent years this film has gained a following so at least a couple of vendors buy new stock and package it as 100' bulk as well as standard cassette loads. Alas, it is no longer a bargain. Standard rolls (36 exp) cost more than Ilford or Kodak films and 100' is hovering between 90 and 100 USD. The film fits neatly in ISO between Plus-X and Tri-X with lower contrast than either. A worthwhile film, if you don't mind spending the money.