Elegoo Centauri Carbon PTFE Guide holds the PTFE at the correct angle to feed filament through the filament sensor from under the spool vs over the top of the spool, as the factory designed. I made this because I am using a ball bearing spool holder and when fed from over the top, my filaments were unspooling too rapidly causing tangles and print errors. 

You will need to purchase new PTFE tubing to lengthen your factory PTFE tube by a few inches. 

Will work with the factory side cover fastener screw. Simply just install. 

It was specifically designed to be quite snug so the PTFE tube holds firm. The screw hole is specifically designed to be just snug enough to barely cut threads into the hole of the guide. 

I printed in PLA.

Hundreds of hours on this design with zero issues. I love the under spool feed MUCH BETTER.

Happy Printing!