White prewound bobbins, cardboard sided, with plastic core.

125 yards of premium quality poly filament thread on each bobbin.

L size - universal for most embroidery machines. Good prewound bobbins are wound by high tech machines which provide a smooth, uniform wind.

The result is much more thread on the bobbin than a self-wound bobbin.

Difference between plastic sided and cardboard sided bobbins:

Plastic bobbins are reusable; cardboard bobbins are disposable.

Some machines, especially Pfaff (2124, 2170, 2140), work better with the cardboard-sided bobbins.

Cardboard sides provide more friction and backlash is usually not an issue. If it is, the bobbin tension may need to be tightened.