The Alpine Type-R SWR-1242D subwoofer features dual 4-ohm coils, an RMS output power range of 200-500 watts, a frequency response of 25-500Hz, and 85dB sensitivity. The subwoofer has a 12.0¿ diameter, with a pulp cone reinforced with Kevlar material. The cone is encased in a sturdy aluminum frame with perimeter venting and heavy-duty rubber surround material. The subwoofer is designed for use with both sealed and ported boxes. The manufacturer¿s recommended sealed-box volume is 0.7 to 1.0 feet and the recommended ported-box volume is 0.75 to 1.75 feet. The SWR-1242D has a heated transfer plate and a multi-stage ventilation system that includes coil venting, leg venting, and pole venting, to reduce overall heat and improve power handling. The subwoofer comes with a one-year manufacturer¿s warranty. Overall, the Alpine Type-R SWR-1242D subwoofer provides rich, deep bass and is a stylish addition to an existing car-stereo system.