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Polk Audio PSW10 10" Powered Subwoofer, 100W Peak Power, Compact Design, Easy Setup with Home Theater Systems Black PSW10 - Best Buy
8 Inch Subwoofer Shell Home Subwoofer Empty Box Suitable for Outer Diameter 208-210mm DIY Speaker Empty Wooden Box Speaker Shell _ - AliExpress Mobile
Subwoofer Enclosure Design: Bending the Rules to Maximize Output - DD Audio