This allows you to change filaments during print. This modification lets you see the filament enter the extruder gear and guide bearing area as it passes though to the heater nozzle sleeve. This takes all the guess work out of changing filaments, especially during printing. Another reason this is a great upgrade, this eliminates the need to pull filament out of the tube when its hot to change it. which, can gum up the tube. Over time you will them have to replace the tube or whole heater nozzle assembly.
Enjoy this project?