These Response woofers are excellent for replacement or for new speaker design constructions. Not only are they price competitive and perform very well, but they also look fantastic! The concave treated paper cone matched with rubber surround provides smooth overall response. Equipped strong steel frame baskets, high power magnet and voice coils, these drivers will produce massive quantities of clean bass output for any musical application. Resonant Frequency 67.6Hz Nominal Impedance 8? Recommended Speaker Box Volume 7.31 Mounting Hole Diameter (B) 136mm Driver Material Coated Paper Mechanical Q (Qms) 1.4 Magnetically Shielded Speaker Type Woofer Driver Driver Channels Single Driver Total Q (Qts) 0.47 Electrical Q Factor (Qes) 0.72 RMS Power Rating 50W Equivalent Volume (Vas) 7.27l Frequency Response 70Hz-7kHz DC Coil Resistance (Re) 6? Side-to-Side Diameter (A) 145mm Cutout Diameter (C) 120mm Insert Depth (D) 65mm Cutout shape Round