The attractive, quality exhaust mufflers are made of rugged, heavy-duty construction. The top and bottom covers are of cast aluminum with a metal perforated housing to provide heat resistance. The device features zinc plated steel tie rods and nuts. The mufflers minimize the noise level by 17-22 decibels at 90 psi in-line pressure with little impairment of operating efficiency. The modules are supplied with NPT male connections.