This part helps with the filament guide tube to be closer to the middle of the spool. It helps with the spool spin smoother.
The part is printed upside down. The part goes behind the Makerbot Repllicator 2 printer. Remove the filament guide tube from the back of the printer. You do not need to remove the filament from the tube. Turn this part upside down so that the two posts point down and the semi-circle groove points toward the back. Slide the two posts into the holes in the printer's body. The rectangle between the two posts is for the large cable bundle. Once the posts are in the printer body holes, push the filament guide tube into the groove. Happy Printing.