Y-Junction for PTFE Tube to M6 Hotend

When using a second extruder, this y-juntion allows the use of a second material by retracting one filament behind this junction and feeding the other.

For my personal use, i have switched to the version with 3 couplers, as I need a ptfe tube inserted into the hotend to not clog. 

→ https://www.printables.com/de/model/175002-y-junction-for-ptfe-tube-to-ptfe-tube