This is a filament sensor for the LGX Pro/Metal extruder. You need a microswitch and a 5mm ball bearing. I found that you may need to drill out the hole for the ball bearing a little in order to get the switch to trigger smoothly when pushing filament through.

You will need some 2mm spacers if you aren't using the Wishbone toolhead, as this is designed to go over its mounting points.

Other than that, it operates just like most of the filament sensors out there :)

Happy printing!