Detachable film magazines allow the photographer to exchange exposed film for unexposed in seconds, or change between film types, lengths, and formats without losing a single frame. Carrying extra, pre-loaded film magazines effectively increase your readiness and efficiency, in the studio or in the field.
Film magazines also broaden the scope of H cameras allowing them to tackle areas where digital backs are not always suitable; specialist films for scientific or other applications, long exposures, night photography etc.