Skar Audio EV-12MB S4 12" Single 4-Ohm 500W Shallow Mount Loaded Subwoofer Enclosure 12-Inch Loaded Subwoofer Enclosure System Frequency Response : 20 Hz to 250 Hz Pre-Loaded EV-12 S4 - Single 4 Ohm 12" 400 Watt Subwoofer Sensitivity (1W/1m) : 88.0 dB Tight, accurate bass reproduction from a shallow and compact down firing enclosure design