Sundown Audio Z v.7 18"The Z v. 7 is the third step up in Sundown's 2025 "ultra high excursion" sub woofer lineup after the M and X v. 4 series. All models (12,15,18) feature our custom tooled and patented frames (US Patent Numbers D691597, D691598, and D741841) the Sundown mega platform. Please note the Z v. 7 is not available, aside from special orders, in 10s due to the motor size. We mate these new platform frames to a quad stacked 265mm (10. 43) diameter motor