O2 OW15 15inch. Subwoofer, Dual 4 Ohm Voice Coil (O2 OW-15) (SINGLE PIECE) Size: 15 inch. Subwoofer Impedance: 4 ohms, dual voice coil Max power: 1400 W Freq. Range: 37 Hz - 500 KHz Sensitivity: 91 dB