A Spacer that slips into position on the yoke and prevents the yoke from being ground on the knurled spindle if the filament completely retracts on retraction during a change.although the STL file is 10mm deep, build at 0.1mm steps and with 100% fill, then use pause at Z at the correct height or cut off object bottom.I designed this after my yoke got the tip ground away on a material change retraction, I used 'Ninjaflex semiflex' to set up the distance i required that still allowed for for a little more friction to be added.I intentionally made the spacer yellow, the Lime green Yoke is my modification to Roberts' that fits a nyloc nut in the rear (Lime green was the filament i had to hand).