DuraBlack 7″ Black Elbow – 90 Deg The DuraBlack 7″ Single Wall Stovepipe 90 Degree Elbow is a component that is used in a typical venting installation. The 90 degree elbow offsets obstructions as needed. The angle is not adjustable and is not recommended for rear exit appliances. Features: Type: Elbow. Finish: Black. Offsets Obstructions as Needed. Used in a Typical Venting Installation. Specifications: Angle: 90 Deg. Inner Diameter: 7″.