These exhaust flanges are available for Continental or Lycoming engines, for building your own exhaust are available in mild steel or stainless steel. The stainless are made from 321 stainless steel and are 1/4″ thick. MILD STEEL: Continental – 0-200, 0-300, C85, C95 and E225 series. Lycoming – 0-235 to 0-540. STAINLESS STEEL: Continental – E225 series 0-200, 0-300, C85 and C95. Lycoming – All through 0-540.