(EIA426B Specification, 1.6kHz @ 18dB) Resonance: 540Hz Usable Frequency Range 1.2kHz-20kHz Recommended Crossover 1.2kHz/18dB or 1.8kHz/12dB Sensitivity: 106.1dB (1W/1m across 1.2kHz-20kHz) Magnet Weight 34 ounce Voice Coil Diameter 2", 51mm Re: 6.1 Overall Diameter 5.25", 133mm Mounting Holes Diameter 2X 1/4-20 or 3" M6 Mounting Holes B.C.D. 3" or 2.25" Mounting Thread 1 3/8" 18 NEF ext. Depth: 2.2", 56mm Weight: 5 lbs., Gross 5.76 lbsMaterials of Construction Voice Coil Former: Polyimide Diaphragm Material: Titanium Magnet Composition, Ferrite