This includes everything you need to install the Chase Bays Polypropylene Reservoir on a Tilton/Wilwood Inline or Pass-Thru Master Cylinder. The reservoir is formed from extreme high heat resistant Polypropylene, the same material used on our race proven Dual Piston Manual Brake. These used to be solid aluminum but after plenty of input we changed to a visible Motorsport grade material so you can easily see fluid levels. We love the change! The reservoir cap is billet aluminum with proper internal diaphragm, anodized in our signature Chase Bays semi-gloss black...laser etch with Chase Bays 360º logo.