This is a modification for the Makergear M2 printer to be able to hold the mini rolls of filament. (Like the 618 nylon 1lb roll) This mod will work on the standard M2 spool holder without modification as well as.This design is retractable so just swing it out of the way when you are not using it. Made with sturdy tri lobe design for added strength. (And it looks cool) Will work for rolls with a center hole of 17.5mm or larger that are up to 80mm wide.