Ender 3 Bowdenfitting

These are Bowdenfittings for the Ender 3.
The Ender bowdenextruder has quite a few problems, one of them beeing, that the fittings don't grip the bowdentube firm enough. As a result, the bowdentube moves for and back, and you need a lot of retraction to stop dripping and stringing.
These fittings fit the extruder and the hotend. To have a strong grip, they use teeth on the inside, holding the tube firmly without damaging it.
To get the right tension on the tube, tighten the nut a little, mark a point in the tube, print something, and have a careful whatch, whether it moves or not. If it does, tighten it some more.