This is a Filament Relocator attachment for the "remixed" X-Axis Belt Tensioner endcaps (preference to the "Final X-Axis Belt Tensioner").
Fairly simple:
Attach this to the supplied accessory mounting holes
Bowden Tube from the Extruder to this mount
Use the Z-Axis Filament Comb if you are using the OEM Z-Axis endstop sensor (to prevent twisted filament from getting between the gantry and sensor, which is Bad).