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 69.8Hz Nominal Impedance 8? Recommended Speaker Box Volume 80l Mounting Hole Diameter (B) 245mm Driver Material Coated Paper Mechanical Q (Qms) 1.01 Speaker Type Woofer Driver Driver Channels Single Driver Total Q (Qts) 0.32 Electrical Q Factor (Qes) 0.47 RMS Power Rating 225W Equivalent Volume (Vas) 21.76l Frequency Response 40Hz-1kHz DC Coil Resistance (Re) 5.41? Side-to-Side Diameter (A) 258mm Cutout Diameter (C) 258mm Insert Depth (D) 110mm Cutout shape Round Attachment / Securing Method Screw Down Mounting Method Front of Panel Diameter 258mm