10" Single 4 ohms TR55 Thunder Round Series Subwoofer Power Handling: Peak: 600 watts RMS: 300 watts Impedance: Single 4 ohms Polypropylene cone woofer Stitched NBR surround Die-cast, stamped aluminum basket 8-gauge nickel compression terminals Rubber magnet boot ALDS (Asymmetrical Linear Drive System) Flat progressive spider Extended pole piece for smooth, linear, piston like drive Exclusive spider plateau venting cooling system 1.75" High temperature single 4 ohms voice coil 60oz. Magnet Frequency response: 35-150 Hz Sensitivity: 85 dB