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 23.1Hz Nominal Impedance 8? Recommended Speaker Box Volume 135l Mounting Hole Diameter (B) 294mm Mechanical Q (Qms) 3.46 Speaker Type Woofer Driver Driver Channels Single Driver Total Q (Qts) 0.36 Electrical Q Factor (Qes) 0.4 RMS Power Rating 225W Equivalent Volume (Vas) 57.61l Frequency Response 28Hz-550Hz DC Coil Resistance (Re) 5? Side-to-Side Diameter (A) 311mm Cutout Diameter (C) 281mm Insert Depth (D) 142mm Cutout shape Round Attachment / Securing Method Screw Down Mounting Method Front of Panel Diameter 311mm