Steel. Complete kit with everything you need. Includes 2 flanges (84-03 style/17-23 style) and 2 retaining rings. Note: 84-03/17-23 'Early Style' steel and 04-17 'Late Style' plain aluminum exhaust flanges are interchangeable. Late Style flanges are thicker and designed to help prevent bending of the exhaust flange. All will fit all 84-up Big Twin and 86-22 XL Sportster models. M8 models are equipped with the 'early style' steel flanges again.
