This modified RB67 70mm back shoots 6x9 format, for the largest size available in any medium format 70mm back! When we modify these we disable the internal frame counting/locking mechanism. Frame advancing is instead measured by ending the lever’s stroke at a printed line on the back (different lines are given for different portions of the film load). In practice this is quite easy. Unlike the original back, our version can be used with all types of film (perforated or unperforated).
This back works on all RB67 cameras, as well as all Mercury cameras and others that use the Graflok 23 back mount.
When our limited supply of backs run out, this will be discontinued.