This is a tiny 'shunt' that fits into the feed cavity in my Printrbot Jr V1 extruder (which I believe is a 'Wade' type). They're made extra long as I'm sure there are some with variations of this type of extruder. Print and cut to desired length. Just slip this into the shaft below the hobbed-bolt and then feed your NinjaFlex (or filaflex, haven't tested with that). So far I've had no slop or binding with it once it was cut to the right length. Try it out or remix it so we can get all of our extruders to work with awesome new types of filament.