Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Neo Driver 4 Ohm Low distortion, full-range 65 Hz to 17 kHz performance Rubber-edged black anodized aluminum alloy cone Large excursion capability-4.6 mm Xmax, 25 mm peak Self-shielded Neo-Balanced motor structure with copper alloy shorting ring 1&quot; 4-layer underhung voice coil with polyimide former