Cobra 6053B - 3 in. Slip-On RPT Exhaust Mufflers fits Harley-Davidson Rocker FXCW/C - BlackThe RPT slip ons make use of all of the high tech features of Cobra's regular three inch slip on mufflers, including two inch constant velocity cores for exceptional sound and performance, as well as the bonded e glass and stainless steel mesh The RPT designation comes from adapting the design from our Race Pro four inch muffler into this three inch size. The bodies begin as three inches at the front until they expand to three and a half inches at the