Enjoy the flexibility to switch between different thread and colors seamlessly with a set of four SINGER Class 15 Metal Bobbins. These replacement sewing machine bobbins are a must-have addition to your sewing supplies, perfect for both novice and expert sewers. Class 15 bobbins are flat on the top and bottom and are commonly used in home sewing machines for various sewing projects, from simple repairs to complex garment construction. Compatible with SINGER models that use a metal class 15 bobbin and Brother machines XL3010, XL3022, and VX1120, these bobbins offer great versatility. Please consult your machine’s manual to determine compatibility. In machine sewing, the bobbin thread forms the bottom part of your stitches, working with the top spool thread for strong, consistent stitches. Made from high-quality metal, these bobbins ensure smooth thread winding and unwinding, preventing stitch irregularities and machine jamming. Using SINGER Bobbins is simple: wind your thread onto an empty bobbin, ensuring it is correctly seated in the bobbin winding tension disk of your machine. For best results, use bobbins that match the class/style of those that come with your machine and wind thread onto empty bobbins only, ensuring proper tension. Replace any bobbins that become chipped, bent, or damaged. Whether you're creating clothing, quilts, or DIY home décor, the pack of 4 SINGER Class 15 Metal Bobbins delivers professional results with ease.