Material: 409 Stainless Steel Inside Diameter: 3" Bi-Directional OUR MOST AGGRESSIVE muffler and with virtually no restrictive qualities,the Widowmaker 6" (a.k.a. "THE NEIGHBORHATER") may be small... butpacks a big sound! With a compact 6” x 5” footprint the Widowmaker 6" isideal for tight space and, with Black Widow's patented internalhourglass design, reduces the opportunity for drone. All Widowmakermufflers are backed by Black Widow's Lifetime Limited Warranty. Go to Warranty on our website for details. NOTE: Because Black Widow mufflers are universal and not a direct OEM fit, we recommend installation by a qualified muffler shop.