Looks like a combiplan holder adapted to a Paterson tank. The question to me is why.

I am lucky enough to have about 8- 4x5 hanger holders, and a pair of tanks. One will hold 6 hangers and has a daylight light trap cover.

I guess this thing would allow you to load the holder and then do the rest in a daylight tank. It sort of implies that you are shooting 4x5 and developing your own film without access to a darkroom, which seems a strange combination to me. The thought of loading such a holder and getting it into a tank in a changing bag seems to leave a lot to get snagged on something along the way.