DURABLE CLASS 15 BOBBINS FOR LONG-TERM USE: Our Sewphee Genuine Metal Bobbins are crafted from galvanized cold-rolled steel. These compatible singer bobbins resist wear and cracking, outperforming plastic alternatives. Designed for front-loading machines only; not for drop-in systems RELIABLE STITCHING WITH SMOOTH THREAD TENSION: Heavier class 15 sewing bobbins reduce vibration and deliver stable tension, minimizing skipped stitches. Bobbin size: 0.8 IN diameter, 0.25 IN inner hole, 0.45 IN outer width, 0.39 IN inner width HEAT-RESISTANT AND WARP-FREE: Designed to resist the heat generated from prolonged high-speed sewing. Our Class 15 bobbins maintain their shape and deliver dependable performance over time. SMOOTHER THREAD RELEASE: The polished metal surface of our 2518A / 2518T sewing machine bobbins allows even thread release, while reducing snags and interruptions to ensure seamless sewing results PACKAGED IN CANADA – PRECISION MADE IN TAIWAN FOR TRUSTED FIT: Compatible bobbins for Singer sewing machine 4423, 4452, 4432. Our universal bobbins are the same size as bobbins for Brother sewing machine. We STRONGLY RECOMMEND that you check your sewing machine manual to confirm compatibility with these sewing machine accessories Experience professional-grade sewing results with Sewphee Class 15 Premium Metal Bobbins—the ultimate choice for sewing enthusiasts, hobbyists, and dressmakers. These bobbins are expertly crafted from galvanized cold-rolled steel for superior durability, ensuring they stand the test of time even with high-speed sewing. Perfect for Singer, Brother, Janome, and Kenmore machines, our bobbins are universally compatible with many top sewing machine models. Whether you're working on intricate fashion projects or basic home crafts, our bobbins ensure smooth, reliable stitching every time. With a heat-resistant design, these bobbins resist warping and deliver consistent thread tension, making them ideal for heavy-duty sewing tasks. Their smooth metal surface ensures a hassle-free thread release, preventing tangles or snags, while the polished finish enhances machine performance and stitch quality. Choose Sewphee Class 15 Premium Metal Bobbins for your sewing machine accessories and supplies and enjoy smoother sewing results for all your creative projects.