These set of models do a few things, One the chain connector model allows for the popular Neptune link and chain guide to be mounted to the linear rail plate from the TBStron3D linear rail upgrade kits. Should be applicable to all kits but I've only tested the 3 plus one.

The adapter utilizes tapered m3x12 screws that came extra with my kits. But could be easily remodeled to accept different m3 sizes. main thing is you would want about 5mm of screw poking out the bottom

Second the arms and sensor cover move the filament run-out sensor to be directly placed over the extruder. Mainly shifted this to allow for more filament to be used at the end of the spool before the sensor is triggered. The metal plate on the sensor does need to be removed to slot the rest of the assembly in.

The wiring does need to be moved if you would like this orientation, about a 12" extension to the wire is needed. I cut and soldered the extension in my case.

The chain adapter will function stand-alone but the sensor cover will not due to it needing to be mounted to the adapter.

Adapter is built on the link and chain model: https://www.thingiverse.com/thing:6305733