DB Bass Inferno BI40 4-Way Speakers: * Silver poly-injected cone woofer for rich bass response with butyl rubber surround * 1.25" Mylar mid-range * Dual 0.5" Piezo dome tweeters * Nominal Impedance: 4 ohms * Size: 4" * 150W max * Frequency Response: 45Hz-20kHz * Sensitivity: 89 dB