Made of High Quality Mild Steel with Computerized Mandrel-Bends for Strength and Durability. Maximizing Smoothest High Exhaust Air Flow Rate. Slip Fit Joints to Provide Easiest Fabrication. Four 48 Straight Pipes. Four 90 Degree Pipes. Four 45 Degree Pipes. Four 180 Degree U-Bends. 4 X 48 Straight Pipes. 4 X 90 Degree Pipes. 4 X 45 Degree Pipes. 4 X 180 Degree U-Bends.