"18 SOUND 8MB720-8 8-inch Woofer Midbass Driver High Power Octragon Shape 250 Wrms 500 Watt capability 8 ohm || 18 Sound’s 8MB720 mid-bass transducer is a state-of-the-art 8-inch ceramic midbass driver that combines excellent linearity with high power handling capabilities (500 W program power), very low distortion and reduced power compression . The 51mm (2 in) employs Interleaved Sandwich Voice coil (ISV) technology. The cone is treated against aggressive weather conditions. The 8MB720 is an ideal choice for high performances compact three-way systems. || || FEATURES || 99.5 dB SPL 1W-1m average sensitivity || 500 W program power handling || 51 mm (2 in) Interleaved sandwich voice coil || Weather protected cone and coated plates || Suitable for high performance three-way systems || DESIGN || Surround Shape : Triple roll || Magnet Material : Ferrite || Recommended Enclosure : 10.0 dm3 (0.35 ft3) || Recommended Tuning : 120 Hz || || SPECIFICATIONS || Nominal Impedance : 8 Ω || Minimum Impedance : 6.3 Ω || Nominal Power Handling : 250 W || Continuous Power Handling : 500 W || Sensitivity : 99.5 dB || Frequency Range : 150 - 3500 Hz || Voice Coil Diameter : 51 mm (2.0 in) || || PARAMETERS || Resonance Frequency : 108 Hz || Re : 5.2 Ω || Qes : 0.35 || Qms : 4.6 || Qts : 0.32 || Vas : 9.0 dm3 (0.32 ft3) || Sd : 227.0 cm2 (35.19 in2) || η₀ : 3.1 % || Xmax : 2.25 mm || Xvar : 3.0 mm || Mms : 18.0 g || Bl : 13.4 Txm || Le : 0.11 mH || EBP : 308 Hz || || MOUNTING AND SHIPPING INFO || Overall Diameter : 225 mm (8.86 in) || Bolt Circle Diameter : 210 mm (8.27 in) || Baffle Cutout Diameter : 186.0 mm (7.32 in) || Depth : 105 mm (4.13 in) || Flange and Gasket Thickness : 11 mm (0.43 in) || Net Weight : 4.6 kg (10.14 lb) || Shipping Weight : 4.2 kg (9.26 lb) || Shipping Box : 235x235x150 mm (9.25x9.25x5.91 in)"