18-in next generation high performance subwoofer, specifically designed for high SPL very low frequency applications in either a reflex, bandpass or horn loaded configuration - Walmart.com
JBL VRX915S 15-in Bass Reflex Subwoofer, White - Westlake Pro
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Yorkville SA315S Synergy Array Bass Reflex Powered Subwoofer 6500 Watt Speaker Cabinet | Digital DJ Gear
Pioneer Pro Audio XY-115S 15-Inch Bass Reflex Subwoofer, Black - AVLGEAR.com
FBT VHA 118 SA - 2500W 18" Processed Bass Reflex Active Subwoofer