Sometimes it happens to see the image of something strange that captures your attention; you do a research and you end to find nebulous and contradictory information.
This is what happed for the Scubapro Mark VIII regulator, designed in 1972 by Tony Christianson, for which the company deposited, the same year, a request of patent. It was a servo-assisted balanced model, from which the Pilot derived. It appeared for the first time in the Swedish catalog of 1975/1976, then in the Italian Scubapro catalog of 1979 under the name P.V.B. (Pilot Valve Balanced). Nobody knows something about it; there is no proof that it was produced. The most probable hypothesis is that, in that period, the company was trying to change the Pilot not to pay the huge rights to Christianson, due because of the contract. In fact, in the mentioned catalogue, Pilot there isn’t anymore, changed only in the 1980 edition by the new Air 1.
Slight better situation for its first stage. Mark VIII was identical to the Mark V except for the tower with the medium pressure exits, here fixed instead of rotating. It shows in the 1980 catalogue, coupled with the 108 second stage; however, we must put attention to the particulars. The one shown in this picture is the first type with large holes, surely never sold. Shortly after, the version with "Spec" cover appeared, that is with small holes, following the technical concepts of that moment; probably, some examples were sold of this type.
Whoever finds in its drawer or discover in a flea market the Pvb second stage or the Mark VIII first stage, he should reminds that these are really rarities.