SB18m is the recommended subwoofer for the ARCS WIDE and ARCS FOCUS line sources, and other mobile systems. It allows extending the operating frequency range of the system down to 32Hz. It features one 18-inch speaker in a dual bass-reflex tuned enclosure. It provides impact, sensitivity, low thermal compression and reduced distortion. One of the vents features a progressive profile allowing laminar airflow and reduced turbulence noise, even at the highest operating levels.