Modular Systems
Since the Metz 54 MZ-4i is based on the SCA system of interchangeable modules, it has a whole little universe of add-on possibilities. This would make particular sense if you use multiple camera systems (e.g. also Canon or Nikon) or if you have some of the other SCA-capable Metz flashes.
Promaster's 5000 series is also based on a (different) modular system.
