This is a 1KG spool holder that uses 4 608zz bearings and includes an embedded spacer as part of the print itself so just push the bearing from the bottom into place and optionally use 4 4mm x 20mm screws with 4 4mm lock nuts for additional strength. The top part of the holder has a lip so if the spool slides over it will still stay on top of the bearing. Glides like butter. Designed in Fusion 360.