Polk Audio AA5252-A MM5251 5.25-Inch System Component System Neodymium Magnets a rare earth metal offering exceptional strength to performance ratio, found only in the most exotic speakers, saves tremendous weight. Dont let the sound system weigh your vehicle down. Carbon Composite Basket based on the spokes of a wheel is lightweight, will not flex during peaks and looks great! Dont be afraid to show off the back of your woofer. Klippel Optimized Components using a state-of-the-art Klippel Distortion Analyzer, Polk engineers were able to optimize the woofers motor structure, voice coil alignment and suspension for the best possible performance, even at extreme listening levels. Woven Glass Composite Cones feature tremendous stiffness-tomass ratio. Lower mass means faster transients and finer detail. Large-Diameter Voice Coils (30mm) in drivers increase reliability and power handling capacity.