This sits in-between the two penny washers that are normally used for the clamp.There are T5 and GT2 versions.Changed from drawings, now has a cut along the bottom of the part, so that there is space between the part and the x-axis frame.Print 2 off.Drill out hole to 4.2/4.5mm.Dismantle x-axis clamps.Place part in-between the two penny washers.Fit back onto carriage, rotate parts to align with the belt, and tighten to the carriage.