Here you can see the Bondtech inlet adapter for 6mm PTFE tube typically used for 3.0mm filament
With this adapter you can use the Bondtech Dual Drive Extruders with a Push-fit for the bowden tube in the groove mount where the Hot-end is located. This is an item the Ultimaker and BCN3D Sigma users will need.
The fancy plug is CNC-machined in aluminium and has a mounted Push-fit connector for 6 mm tube.
Of course, if you prefer to make your own adapter here is a link to the STL-file: