Vertical M-adapter for Mamiya Universal

I'm an owner of a Mamiya Universal with both pola-back and the traditional s-shaped film backs, which I occasionally use.
Some time ago I came across a vertical M-adapter I couldn't resist to buy, but I still have no idea on what accessories might be usable with this adapter. Its neither the film backs or the pola-back i own for sure.
Can anybody help me?