Cobra Powr-Flo 4.5 in. Slip-On Mufflers for Harley Davidson 1995-2013 FLH, FLT 4.5in. body tapers to 4-inch round at the front 4.5in. machined aluminum, thin-line tip 3 in. high-flow core for superior performance Acoustical engineering developments allow an incredibly deep sound because of intense, class-leading resonance absorption and prevention Uses proprietary materials with specific acoustical dampening and thermal insulation properties