The QSC HPR181i 18" Powered Subwoofer features an internal 700 watt class-H amplifier, 18" woofer, a low-end frequency response down to 39Hz and birch plywood construction with 16-gauge, powder coated steel grille. This powerful subwoofer delivers power and sound that rivals 18" powered subs, and is a well suited choice for professional club installation, mobile sound reinforcement for DJs, live performances and more. A top mounted 35mm pole socket is featured for sub/satellite speaker mounting.