Embedded Bowden Coupling for Metal

The couplings are designed to take PTFE tubing with an outer diameter of 3.18mm for 1.75mm filament, and 6.35mm for 2.85 mm filament. 
 
These fittings are used in both types of the 1.75mm V6 hotends, the 3.0mm Bowden V6 hotend, and the Cyclops/Chimera/Kraken/ Hemera HotEnds.