This is modified version of fan duct mod from https://www.thingiverse.com/thing:2814127

Original part does not fit well to new Ender-3 revisions with silicon sock on nozzle. First - it touches the silicon sock, and melts there (made from ABS and printed ABS). Second - too small width of mount holes - it can be mounted but hard.

This version has also shorter duct. Silicon sock on the nozzle of Ender-3 has very pool heat isolation, so normal version of this duct was heating a lot. Air inside was heated very quick, so cooling wasn't effective. This shortened version isn't heating so much from silicon sock, so air that exits duct is more cooler - pressure of air hitting print is smaller, but I think that is enough and still better than stock.

I have also made an water test for air flow. It looks that air is hitting almost directly bellow nozzle.