B&C 21SW115-8 21-Inch 3400 Watts Neo Woofer 3400 W continuous program power capacity116 mm (4.5 in) split winding copper voice coil33 - 1000 Hz response97 dB sensitivity 60 mm peak-to-peak excursion before damage Neodymium magnet allows a very high force factor and linear excursion Double silicone spider with optimized compliance Ventilated voice coil gap for reduced power compression Aluminum demodulating ring for very low distortion