This 4-inch slip-on system gives you the sound and look you would expect from a premium muffler, at an incredibly low price.The 4-inch diameter, 909-Twins feature a unique scalloped and smooth rolled outer tip that is matched with a scalloped inner tip. This "Twin" tip design gives an elegant look, especially because there are no visible outer screws securing the core. Cobra uses a 2.25-inch louvered core for its traditional and recognizable sound. These mufflers carry Cobra's limited lifetime warranty, too. Incredible styling, great sound, lifetime warranty and a low price. Tough to beat.Rolled and scalloped outer tip.Matching scalloped inner tip.Chrome or black finish.Cobra's exclusive constant velocity louvered core.Cores secured on the inside with no outer screws.Classic sound, deep yet aggressive.Sold in pairs.Limited lifetime warranty.