Sewing spool size: Single sewing spool with 20 mm diameter, 10 mm height, center hole diameter 6 mm. Sewing machine spool application range: High quality sewing machine spool, very suitable for sewing factories, home sewing machines, sewing and induction thread collection, DIY and other projects. Compatible with all standard household sewing machines. Sewing machine bobbin material: High-strength, high-quality plastic sewing bobbins have a longer service life and can be reused, while the transparent colored sewing bobbins do not affect the actual color of the sewing thread. Scope of delivery: Includes 25 sewing machine bobbins, 1 transparent storage box for perfect storage of the sewing machine bobbins. Note: Singer 964, 974, 8019, and 9032 are not applicable.