AGS Stainless Steel fittings are made of 303 Stainless Steel. It’s a high-quality non-magnetic stainless (austenitic) that provides nearly twice the tensile yield strength (resistance to breakage) as mild steel, and excellent resistance to corrosion and rust. Stainless steel tube nuts, adapters, and unions will not rust or corrode and are stronger than either mild steel or brass fittings. AGS stainless steel fittings are compatible with all steel, nickel-copper, PVF- coated, and stainless-steel brake lines. Perfect for use with all cast iron, steel, and aluminum calipers, wheel cylinders, and clutch slave cylinders. Upgrade to stainless steel for long-term beauty and peace of mind. AGS Stainless Steel Fittings are polished to a stunning finish. Pair with AGS Stainless Steel or NiCopp® tubing for all automotive applications where appearance and performance is critical.