The 151ST70 features a proprietary high excursion 15" aluminum driver mounted within an aluminum sealed band-pass enclosure. Engineered for direct burial placement, the compression design creates unrivaled low end frequency response, and nearly complete invisibility. You can install up to (4) of these subwoofers on a single run of 14/4 speaker wire when paired with our M1000 DSP amplifier! The external hooded port, aircraft/marine grade aluminum enclosure and stainless steel hardware provide for increased protection in extreme weather.