This 3/8-24 Banjo Bolt is Zinc plated steel for a forever finish. Includes 2 aluminum crush washers. These brake adapters are manufactured from quality-grade steel machined to mil spec tolerances and zinc coated for a durable, tight connection. No matter what the job, connecting P.T.F.E. lined hose to calipers and wheel cylinders, mounting it to hard lines, or just replacing that leaky fluid banjo bolt.