The Procella V6 subwoofer extending below 18Hz (bass module for P28)
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GODFATHER Subwoofer – American Car Audio
HECO New Phalanx 302 Hi-Fi subwoofer Black 400 W 18 Hz - 150 Hz | Conrad.com
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HECO New Phalanx 302 Hi-Fi subwoofer White 400 W 18 Hz - 150 Hz | Conrad.com