if you have trouble threading the filament into the bolean tube,this will help you guide it in, the trumpet fits snugly over the bolean tube (the bore in the trumpet is 4.2mm). the only problem is you need to countersink the end of the bolean feeding tube first or you may still encounter threading problems becase the walls of the tube are o.75 mmn thick and the filament tends to catch when you feed it in. 

the new modification makes it so you do not need to countersink the Bowden tube. it makes it much easier when threading the filament into the guide. I hope you find this better….

the old model is the yellow one and the improved model is the white one….