The best way to describe this is via the dimples on golf ball, those dimples at rotational will create lift! The rips of feather of bird will give them the quietness and give the winds a little more lift too. That is why birds like owl have larger feather, but more texturized, while eagle although have super smooth winds top, but all tops of feather are ripped (reduce surface to air drag as the air is being disturbed, it cannot form uniform directional force against it, this is especially true in smaller flight surface). Texturing alone can add 30% in forward efficiency (decrease back pressure drag) as speed exceed 180 mph. The higher the speed, the more effective it gets.
The vane is EXACTLY 14 mm form the feet or 0.5511811" high