FEATURES an aluminized steel case with a 409 stainless steel perforated inner core for high flow and long life - STAINLESS INNER CORE has an expansion joint that allows it to expand and contract with heat to prevent cracking which is common with most similar mufflers - PACKING ...FEATURES an aluminized steel case with a 409 stainless steel perforated inner core for high flow and long life - STAINLESS INNER CORE has an expansion joint that allows it to expand and contract with heat to prevent cracking which is common with most similar mufflers - PACKING MATERIAL inside this muffler is a long strand high-temperature fiberglass to deaden sound and stand up to the test of time - SPECIFICATIONS: 3 inlet / outlet 4” x 6.5” body 9” overall length - THE SAME HIGH-FLOW DESIGN USED in our SRT8 Challenger and 2010-up Camaro SS Cat-Back kits