RING PIECE (Filament spool retainer) 30mm

slides over 30mm filament spool holder to prevent spool falling off (if like me you have lost the nut to screw on the end)

fits my Wanhao Duplicator filament holder.
It says "RING PIECE" around the perimetre, in case you forgot its name...

I dont envisage anyone requiring this part, unless you are butterfingers and lose the 30mm nut from the end of the filament holder.