This is a spacer for the BLTouch Auto-Leveling sensor. I am running a modified X Carriage with mounting holes for the BLTouch and this spacer drops it down to the right height for the chimera style hot end that ships with the Tarantula (50mm from the bottom of the carriage to the tip of the extruder, 34.5mm is the working length of the sensor, making this spacer 15.5mm.) I designed it in Fusion 360, would be great to be run through customizer for other printers. I used ABS for mine.

Hope this helps someone!