This ball winder (Model YBW-B) makes center pull yarn balls with a capacity of about 4 oz. The clamp-on base allows it to be firmly fixed at the edge of tables, chairs, benches, or any other convenient locations. The maximum thickness of table that this can clamp on to is about 1 1/2". It is best to be used with a swift yarn winder (Umbrella or Amish style, both available under Stanwood Needlecraft brand names). But you can easily replace a swift with other devices or just simply your arms. The craftsmanship on these ball winders is superior. The cogwheels of the ball winder are fully sealed in our design so they will never eat your yarn. The cogwheels of a similar model made by our competitors are exposed and may eat your yarn (as shown in the picture).