This custom designed aluminum heat shield is pre-formed to fit all 40 series mufflers. Adding a heat shield to your muffler gives added protection in reducing heat radiated from mufflers and also helps reduce interior noise. May fit all mufflers with an approximate case thickness of 4.00 to 5.00 inches tall, 10.00 inches wide and 13.00 inches in length. Attaches easily with included stainless steel muffler straps.