Six-pack of Proven MX Roll-Off replacement film. Notes: Number of pulls per Film Roll: 55, ±3. Maximum Film travel per pull: 185 mm. Vertical Film height: 31 mm. Horizontal distance between canisters: 147 mm. Important Note: The amount of film traveling across the lens with each full pull will vary from beginning to end of the film cartridge. The reason for this is the diameter of the cylinder that the film wraps around in the "pull-side" canister will increase as you use up the cartridge, which will generate more travel per pull. So, at the beginning of a roll, it may take more than one pull to clear the entire lens, but toward the end of the roll one pull will span the entire lens. This means the effective number of full lens "clearings" will be in the neighborhood of 45 rather than 55. These specifications are consistent with the top-performing competitors out in the field.