A reverse Bowden relieves the the issue of layering artifacts caused by extrusions and retractions pulling on your filament spool. Even with an extremely fluid spool holder there is still some force that is exerted onto the extruder assembly causing small imperfections in your layer heights. Using this will move those actions outside of the extruder in the area between the tube end and the spool. With the constant pressure of the tube you will get far less layering artifacts and more consistent prints.

You'll also need to purchase this kit from amazon or if you have part lying around it should fit as well. https://www.amazon.com/gp/product/B01F1XTRGI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

You only need a couple of feet of ptfe tube but I purchased this just to be safe and I have plenty of excess tube and the fittings are of really good quality.