What can I tell you about this mysterious object? (See my comments on the FM brand)
The parallelogram is a copy of the SunTour Vx, right down to the go-faster stripes - with the curious exception that the adjustment screws have been repositioned onto the outer parallelogram plate. The built up area on the rear knuckle (where SunTour put their adjustment screws) has ‘777’ written in the space. It will not have escaped your notice that, for many years, SunTour used ‘8.8.8.’ as a model/sub-brand name (and Shimano used ‘3.3.3.’). Where SunTour put a ‘V’ logo on the front knuckle of the Vx, this has ‘FM’. The pulley wheels are also stamped ‘FM’. The outer cage has ‘FMAIAL’ stamped on it, although the very few times that I have seen this brand referred to it has been as ‘FMaial’, which would be consistent with the use of ‘FM’ branding elsewhere on the derailleur.
The pulley cage is completely not SunTour and is more like the geometry of the cage on something like a Shimano Exage. The top roller looks to have ended up in a very strange position as the SunTour parallelogram geometry expects a cage with the guide pulley concentric with the pivot.
Finally, the aluminium parts are covered in an extremely high gloss chrome type finish.
All very odd.