Camera Angle Adjuster

[Scooot]

I've just been looking at the system chart for the tak fs60 when including their field flattener and I can see a Camera Angle Adjuster in the Chain. There doesn't seem to be a uk price for them anywhere online although they're $250 in the USA, which seems very dear. Are they really necessary, and does anyone know whether there are other non Tak makes that would work.