The lower part is a bit flimsy (the top part tends to break easily). It`s recommended you strengthen it with a few drops of superglue in that area before applying.
These parts have been tested with the striped version of Medianav grille. The older style with the outer shoulder part might not work, i didn`t try.
Note that the orientation is not arbitrary, there is only one correct way to print the part (check which of the sides is completely planar, the other one has the hook a bit raised).