The NS v.5 is the absolute top-tier driver in Sundown's "ultra-high excursion" sub-woofer lineup with a 3” coil. All models (10,12,15,18) feature our custom tooled and patented frames (US Patent Numbers D691596, D691597, D691598, and D741841). Our proprietary frames allow 4” or more of peak-to-peak mechanical excursion.