Body size: 18" x 9" x 4" Material: 409 Stainless Steel Inlet/Outlet size is "inside diameter" Bi-Directional Our Venom 300-series mufflers are made out of quality brushed stainless steel and, because of their larger body, produce a slightly quieter tone than our Venom 250-series. With Black Widow's straight through patented internal hourglass design, the 300-series allows for optimal horsepower and torque without a harsh drone sound. All Venom 300-series mufflers are backed by our Limited Lifetime Warranty. Go to Warranty for details. NOTE: Because Black Widow mufflers are universal and not a direct OEM fit, we recommend installation by a qualified muffler shop.