Flat spline is an essential component for securely installing screens in porch and patio screening systems. At Metro Screenworks, we offer flat spline in four different sizes — .285, .300, .310, and .315 — to ensure a perfect fit for any screen frame. Made from durable vinyl, flat spline is designed to hold both aluminum and fiberglass screening materials in place, making it ideal for frames with shallow grooves. Whether you're replacing a screen or building a new outdoor living space, our high-quality flat spline provides a reliable and long-lasting solution.