Use a small diameter rod bent 90 degrees at one end as spool holder. Install bracket first then insert rod into bracket as shown in picture. Hub adapter is slightly larger than spool center hole and is designed so it can be sqeezed to fit snugly. Print in pairs. Included STL for bracket uses 1/4 inch rod with 15mm radius bend. Mounting holes are for 3mm screws. Included STL for hub adapter is for spools with a 52-56mm diameter center hole.SCAD file included for your customization.