This is an Extruder build-in Filter for Filament. Just remove the top cover of the extruder and put the element under. it should fit to the square hole. The filament can un-/loaded with mounted element
use a piece of sponge as filter/cleaning element.
There are 4 spikes in the filterhole. Those are to prevent the sponge get out of the hole when filament move backwards.

Mingda D2

Doesn't Matter

Yes

0,12

50%

Adjust size (+- 0,5mm) to fit in the extrudercase window (to compensate production tolerance)
top size for window is 22x36mm.