These novel 4" muffler bodies feature advanced acoustical tuning technologies for a deep rumbling sounds. The 4" round muffler front expands just after the steel clam shell clamp to 4-1/2" diameter. The gloss black finish on the aluminum tip is matched with the gloss black finish on the laser-cut steel strap that tightly encircles the muffler and has built-in mounting points. With its unique strap the Race Pro looks like a radical departure from the norm, when in fact, the Race Pro mounts the same way as nearly every slip-on muffler from Cobra. The strap clamps tightly around the muffler and bolts to the bike's hanger mounts located beneath the saddlebags. PEM fasteners in the wrap make mounting a simple task of threading in a bolt from the upper bracket into the Cobra strap. The mufflers come with 3" cores encased in proprietary Cobra sound tuning materials with specific acoustical dampening and thermal insulation properties.