A simple coupling and union that uses a captive 4mm nut that threads onto the PTFE tube. I couldn't find one that would work for my situation so I ended up with this, works fantastic.

For the coupling you can use on hotends with threaded tops for standard fittings, cut a small pc of tube to to reach nozzle, then thread this in on top with your Bowden tube to your extruder. it doesn't move.

The union is nice for when you just need that little extra but you only have short pcs like I did, threads in nice and snug and lines up perfectly with no gap between the tubes.

FLSUN QQ-S

Doesn't Matter

No

.15

100%

You will need to slice and pause at height to insert the 4mm nut. 1 location on the fitting, and 2 on the union.