This for the Prusa MK3 with the 45 degree factory suggested part cooling upgrade. This is not for the new MK3S.
So the basic part cooling duct was still to small to provide any side and back side cooling of PLA printed parts. This part printed in PETG will fit and clear all parts and provided much better cooling, less stringing and over hangs look great now. one picture shows the factory part cooling duct next to the new design, you can see how much farther back the new design can blow air.
Prt remix of factory part and part new design made in Design Spark Mechanical.