Vance & Hines Blackbird 450 Slip-Ons For Harley Touring The Blackbird Slip-Ons come standard with the most aggressive baffle that V&H has to offer along with a beefy 4 1/2 muffler body so you can be sure they do more than just look good! Features: Massive 4.5-inch muffler bodies Tapered machined billet end caps V&H's most aggressive baffle