This POLK active subwoofer uses an 8" driver with a huge excursion to reproduce 32 hz bass with minimal distorion. Built-in amplifer rated at 100 watts . Powered either from high level speaker terminals or from subwoofer output on a receiver or amplifier. Rear panel controls include level (volume), low-cross frequency point. Dimenstions: 13" deep X 11" wide X 11" high + 1.5" feet. For a demonstration send an email or phone 801 487-3047