Summarywith this part you can keep clean the filament (no dust inside the extruder) 1,75 or 3 mm on your printer. You can place it everywhere....up to you :-) size D24 x 13mmInstructionscut out a little piece of sponge (D20 x 10mm) and put it inside the sponge-holder... make sure that the sponge not opposes friction on the filament