Kicker 47TRTP122 12-Inch Thin Down Firing Subwoofer with CX6605 system amp, KSS6504 KSC6504 speakers and wire kit - Walmart.com
TDX 12-Inch Down Firing Powered Subwoofer Home Theater Surround Sound Black 12" 6956745144216 | eBay
Sundown Audio U12 D4 - Down4sound Shop
Kenwood P-XRW122DB 12" Subwoofer in a Sealed Down-Firing Enclosure with a XR601-1 eXcelon Reference Series Power Class D Mono Amplifier - Creative Audio
Kicker 47TRTP122 Car Audio Down Firing 12" Thin Sub Box w/ Passive Radiator New | eBay
JL Audio 12W0v3-4 W0v3 Series 12" 4-ohm subwoofer at Crutchfield
Kali Audio WS-12 12" Active Subwoofer-EA - Subwoofer - Professional Audio Design, Inc | Professional Audio Design, Inc
SA SERIES
KICKER 48CDF124 Comp12 12" 300w Down Firing Car Subwoofer+Mono Amplifier+Amp Kit - Rockville Audio