Round, button shaped clip with an integral rivet, fits in holes around the upper door window frame.
13H0743 is the clip that is used to hold the upper window chrome, except at the very bottoms of each leg, where three each of the 13H0744 are used. The chrome has to slide down over the washer part of the 13H0744 and then when it is fully in position (downwards), the chrome is pushed against the 13H0743 rivet heads, snapping over them.