SPECIFICATION: MODEL:TRF SPL SW2165CC D0.7 Size: 21nch Cone: Carbon FROM MADE IN EUROPE Surround material: Foam Voice coil made : MADE IN USA or MADE IN GREECE Voice coil dimension : 4.0inch Voice coil layer: 8layer Dust cap : Carbon FROM MADE IN EUROPE Nominal impedance:dual 0.7ohm Voice coil wire:aluminium Spider dimension : 4''ID / 10''OD Spider material : NOMEX Spider layers :5pcs x 2layers RMS Power: 6.500wrms RMS Program: 18.000wrms MAX Watt: 12.000wmax Sensitivity: 94.5dB Vas: 250 L Resonance frequency(fs): 35Hz Frequency range:35-100Hz Mechanical Q factor(Qms): Electrical Q factor(Qes): Total Q factor:(Qts): Xmax: 40mm Force factor: N/A Net weight: 46kg Basket:Die cast Alumium Magnet: Ferrite Magnet:Ferrite ''high performance magnet'' Magnet dimension:Φ280*25mm X 3PCS 1=Outer Dimension: 550mm 2=Mounting Depth: 330mm 3=Magnet Dimension: 280mm 4=Mounting Hole Dimension:500mm