MW19PNW-4. Ventilated aerodynamic cast aluminum chassis for optimum strength and low compression. Proprietary cone material with EGYPTIAN PAPYRUS fibers made in house. Soft, low-damping rubber surround for optimum transient response. Advanced BIMAX Spider for improved linearity. Powerful, optimized, low-distortion neodymium motor system. Non-conductive fiberglass voice coil bobbin for minimal cushioning. Extended copper sleeve on the pole piece for low inductance and reduced distortion. CCAW voice coil for reduced moving mass. Durable silver lead wires spaced 180 degrees for better stability. Ventilated pole piece for reduced compression. High ratio of piston to chassis diameter. Gasket and bolt hole protrusions for reduced connection to the speaker enclosure.