The SINGER Class 15 sewing bobbin set includes 36 threaded Class 15 bobbins as well as a set of three bobbin rings. The three bobbin sets are class 15, and each set contains six black bobbins and six white bobbins, providing a total of 1,800 yards of bobbin thread. Each set comes in its own case, which is made of clear plastic for easily picking out the color thread needed, and the cases have snap-tight latches to keep contents secure. The bundle also includes a set of bobbin rings for easy organization. The bobbin rings are constructed from durable nickel-plated steel. Each ring opens easily, snaps securely closed, and can hold 16-18 bobbins per ring to conveniently transport thread bobbins, add to a sew kit, or hang on a peg near the sewing machine for easy, visible access. No more searching through a drawer or sewing kit full of loose bobbins and other sewing machine accessories to find the right color or thread weight for your sewing project. With this bobbin and storage bundle, your thread bobbins will stay neat, organized, and easily accessible for your next machine sewing project. Details: 39 pieces 1,800 yards of bobbin thread Each bobbin ring can hold 16 to 18 bobbins per ring to conveniently transport thread bobbins Contents: 36 threaded Class 15 bobbins (18 black bobbins, 18 white bobbins) 3 bobbin rings (3" diameter)