Power Rating Watts 800W Music Program 1600W Resonance 25Hz Usable Frequency Range 40Hz-800Hz Sensitivity 97 Magnet Weight 109 ounce Gap Height 0.375", 9.53mm Voice Coil Diameter 4", 101.6mm THIELE and SMALL PARAMETERS Resonant Frequency (FS) 25Hz DC Resistance (Re) 5.20 Coil Inductance (Le) 1.67mH Mechanical Q (QMS) 8.18 Electromagnetic Q (QES) 0.32 Total Q (QTS) 0.31 Compliance Equivalent Volume (Vas) 548.7 liters / 19.4 cu.ft. Peak Diaphragm Displacement Volume (VD) 556cc Mechanical Compliance of Suspension (CMS) 0.29mm/N BL Product (BL) 18.8 T-M Diaphragm Mass Inc. Air load (Mms) 138 grams Efficiency Bandwidth Product (EBP) 79 Maximum Linear Excursion (XMAX) 4.8mm Surface Area of Cone (SD) 1159.0 cm2 Maximum Mechanical Limit (XLIM) 16.0mm MOUNTING INFORMATION Recommended Enclosure Sealed Vented 96-198 liters/ 3.4-7 cu.ft. Overall Diameter 18", 457.2mm Baffle Hole Diameter 16.56", 420.5mm Front Sealing Gasket fitted as standard Rear Sealing Gasket fitted as standard Mounting Holes Diameter 0.28", 7.1mm Mounting Holes B.C. D. 17.25", 438.2mm Depth 8.15", 207mm Net Weight 25.2 lbs., 11.4 kg Shipping Weight 28.9 lbs., 13.1 kg MATERIALS OF CONSTRUCTION Coil Construction Copper voice coil Former Polyimide former Magnet Composition Ferrite magnet Core Details Vented and extended core Basket Materials Die-cast aluminum basket Cone Composition Paper Cone Edge Composition Cloth cone edge Dust cap Composition Solid composition paper dust cap