Make switching thread colors fast and easy by keeping a supply of blank bobbins around.

◦   7/8" diameter
◦   1/4" width between sides
◦   Eight 1/8" diameter holes around perimeter of sides
◦   1/16" diameter threading hole on both sides
◦   1/4" diameter center hole
◦    Fits the Singer sewing machine models 221, 221K, 222, and 301