Easily handles those tiny 4 oz. spools all the way up to 5 lbs. spools. Recommended additional hardware is a 1/8 inch (3mm) steel rod cut between 4.75" and 4.85" (120-125mm). The photo shows a prior version that lacked a built-in mounting bracket to screw this down to a surface with. If you swap spool sizes regularly, this halter can save a minute or so per switch over most other spool holders. Rollers move very smoothly, especially after some light sanding along the layer-start line.