SPECIFICATIONS: MODEL: TRF SPL SW2140NDGE D0.35 Size: 21inch Cone: Carbon FROM MADE IN EUROPE Surround material: Foam Voice coil made : MADE IN USA or MADE IN GREECE Voice coil dimension: 3.0inch Voice coil layer: 8 layers Dust cap: Carbon FROM MADE IN EUROPE Nominal impedance: dual 0.35ohm Voice coil wire: aluminum Spider dimension : 3''ID / 10''OD Spider material: NOMEX Spider layers: 5pcs x 2layers RMS Power: 4,000 wrms RMS Program: 12,000 wrms MAX Watt: 8,000wmax Sensitivity: 96dB Vas: 250 L Resonance frequency (fs): 31Hz Frequency range: 31-100Hz 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: NEODYMIUM Magnet: NEODYMIUM ''high performance magnet'' Magnet dimension: Φ260*30mm X 1SET 1=Outer Dimension: 550mm 2=Mounting Depth: 330mm 3=Magnet Dimension: 260mm 4=Mounting Hole Dimension: 500mm