What you get: The package includes 4 pieces, a sewing machine bobbin case which you can change and replace according to your interests, or share with others. Application: The robbin case is always applied as a spare part for sewing machines with front loading bobbin system, it can also be used as a spare case. Function: Bobbins can stop spinning faster, effectively preventing the bobbin thread from unwinding when sewing operations stop and start. Size: Each bobbin case is about 22.75mm in diameter, suitable for most sewing machines, such as Babylock, Bernina, Frre, Elna, Janome, Kenmore, Singer, etc. Material: The bobbin case is made of stainless steel, durable and very practical, can serve for a long time.