This exhaust system connects to common 4" dryer vent ducting. The fan grill/ air straightener part stops the fan from stirring the enclosure air.
The groove on the hose side part is to help keep the cable tie in place.
You can connect the vent hose directly to the fan side part if you want and not use the hose side part. I made the hose side connector so that I could easily remove the hose and/or attach it to my other printer.
Straightener printed with 5 perimeters, 7% honeycomb infill and no top or bottom layers.