Some of you may already have a Nodal Rail from your past purchase, and would want to invest in something that facilitates its use when you want to get hold of a Multi-row Panoramic Head. PhotosphereSG had worked with Fanotec to come up with this version where essentially you replace the NN3 upper rail assembly and convert it to a arca-swiss clamp rotator.
This allows you to customize a nodal rail that suits your setup. E.g. The SEL1635F4Z (from Sony) has a Entrance Pupil (Nodal point) beyond the upper rail of the NN3.
OR this also allows you the flexibility of customizing an even shorter rail than the original NN3 upper rail to keep your setup as small as the NN3 or perhaps even smaller. This is useful for, say a Voigtlander 15mm F4.5 III lens where you have a relatively short entrance pupil distance where you just need a 100mm nodal rail (including the arca swiss clamp section).