2.5″ 4 layer Anodized aluminum high temperature voice coil Non-Pressed paper cone Double stitched foam surround Dual poly-cotton dampeners Die-cast aluminum vented basket Rubber gasket trim ring Large gauge compression terminals Protective magnet cover Outside Diameter (A) 8.78″ (223mm) Cutout Diameter (B) 7.32″ (186mm) Mounting Depth (C) 6.32″ (160.5mm) GENERAL SPECIFICATIONS Structure 8″ (20.32cm) Woofer Dynamic Power Handling 1800 Watts Nominal Power Handling 900 Watts Impedance Dual 2Ω Voice Coil PARAMETERS Resonant Frequency (fs) 34.109Hz D.C. Voice Coil Resistance (Re) 2 x 3.2Ω Mechanical Quality Factor (Qms) 3.193 Electrical Quality Factor (Qes) 0.615 Total Quality Factor (Qts) 0.516 Equivalent Air Volume to Cms (Vas) 7.375 L Mass of Diaphragm/Coil (Mms) 169.4 kg Force Factor (Bl) 19.44 Sound Pressure Level (SPL) 78.6 dB