To develop this new Illusion Audio speaker line we combined our decades of experience manufacturing high-end audiophile speakers with our passion for maximum performance mobile audio. The development process covered several years and literally months of listening to each individual model to fine tune musical quality and durability. We applied the highest available technologies in construction materials, Finite Element Analysis engineering and manufacturing to develop speakers that are compact and lightweight for easy installation without making any performance compromises. Our artistic design team has paid careful attention to aesthetics, as we feel they are beautiful speakers too! Aluminum coated injection polypropylene cone with rubber surround powder coated steel basket Midbass: Free Air Resonance: 74.66 Hz Nominal Impedance: 4 Ohms Sensitivity 2.83 v @ 1 meter: 90.8 Outside Diameter: 130 mm basket + 150 mm ears Mounting Hole Diameter: 117 mm Mount Depth: 61 mm Maximum Linear Excursion: ± 2.5 mm Tweeter 25 mm aluminum dome 4 ohm Outside Diameter: 48.2 mm Mounting Hole Diameter: 43.5 mm Mount Depth: 11 mm Crossover: Bi Amp 12 dB crossover Tweeter overload protection Dimensions: 131 x 84 x 38 mm Titanium-coated injection polypropylene cone with rubber surround Powder-coated steel basket 26 mm voice coil Driver Specifications: Fs: 74.66 Hz Re: 3.3 Ohms Qms: 2.98 Qes: 0.6 Qts: 0.5 Le: 0.16 mH Vas: 5.56 liter Mms: 10.19 gram Cms: 446 uM/Newton BI: 5.14 Tesla-M SPLref: 90.8 (2.83 volts at 1 meter) Sd: 95 sq cm Xmax: 2.5 mm Xsus: 10 mm Nominal power: 50 Watts Maximum Power: 100 Watts Outside Diameter: 130 mm basket + 150 mm ears Mount Hole: 117 mm Mount Depth: 61 mm Weight: 850 grams