Snap this onto your Printrbot 1.75mm filament spool to save yourself the trouble of taping the end when not in use, or risking your spool uncoiling itself. This may work with other brands of filament if they use the same or similar spool design.Printed solid. To attach the clip to your spool, rotate it 90 degrees from its final position, such that the opening on the spool clip lines up with the outer lip on the spool, the roll it into place. It should snap nicely. Next, snap the end of your filament into the filament clip and you're good to go.