S&S Cycle SS550-0621 Mk45 4.5" Slip-On Mufflers Black w/Black Thruster End Caps for Touring 95-16Mk45 4. 5" Touring Mufflers are the result of decades of riding, racing and tuning. Combining both a stainless steel baffle and fiberglass packing, they create a deep rumble and improved horsepower and torque, all while adding a unique look with styled aluminum end caps. FEATURES & BENEFITS 7 horsepower gain* 4. 5 design with stainless steel baffle and Race TEX cartridge packing Guardian Black finish Tuxedo Black Thruster end cap Removable dB reducer