SD-3 8 D4 - Sundown Audio 8" 300W RMS Dual 4-Ohm SD Subwoofer. Sundown Audio SD-3 8 D4 8" 300W RMS Dual 4-Ohm SD Series Subwoofer. Secondly the entire SD-3 series features an inverted rubber surround – this reduces the space required in front of the woofer to about 1” total (we suggest 1.25-1.5” when possible for the best sound).
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