Elna supermatic sewing machine bobbins

Elna Supermatic bobbins have a groove on the inside of the cylinder which means normal bobbins don't fit on the top winder.  The original metal bobbins are solid on the bottom and have 7 holes on the top side, which allow you to see the remaining thread level without removing the bobbin from the machine.

These bobbins are printed in two pieces without supports and can be pressed together for a tension fit.  It is advisable to use a drop or two of superglue on the central interior column to assure a tight bond.