The WH1-DBL is a double 18 version of our WH-1 folded horn. Colossal in output, size, and weight, this subwoofer is only recommend for use in installation applications of unusually immense low frequency needs. This model has been developed for performance in popular hip-hop clubs where other designs have failed acoustically and mechanically. If you have exhausted your search for a high-output permanent install sub that will literally shake you and your audience, look no further. This is the subwoofer of subwoofers, whose output has been described as "thunderous, earth shaking, and like hearing the voice of God." In our thirty years of low frequency enclosure design, we have never heard anything close to the output that four to six of these subwoofers produce. Our customers have been replacing their expensive, top-of-the-market subwoofers with our WH1-DBL.