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 49.5Hz Nominal Impedance 8? Recommended Speaker Box Volume 19l Mounting Hole Diameter (B) 168mm Driver Material Coated Paper Mechanical Q (Qms) 2.02 Speaker Type Woofer/Midrange Driver Channels Single Driver Total Q (Qts) 0.44 Electrical Q Factor (Qes) 0.57 RMS Power Rating 60W Equivalent Volume (Vas) 19l Frequency Response 44Hz-7kHz DC Coil Resistance (Re) 6? Side-to-Side Diameter (A) 178mm Cutout Diameter (C) 145mm Insert Depth (D) 77mm Cutout shape Round