Spool Holder Gripper / Spacer

I use a lot of smaller filament spools and find that they move left and right on the arm. This occasionally causes the filament to unspool more than needed and it wraps around the arm and stops the filament from advancing. I was using a binder clip, but those caused their own issues. So I designed this simple gizmo that slips on the spool holder and keeps the spool in place. Has to be printed from TPU so it stretches and grips the holder.