Audiopipe TSCVR6 TSCVR Series 6-1/2 inch Subwoofer - Dual 4 ohm voice coils
6.5" NITRO SERIES SUBWOOFER 400 WMAX/200 WRMS DUAL COIL 4 OHM VOICE CO – GENIUS AUDIO USA
DC Audio 6.5" Subwoofer — DC Audio
6.5 Inch 100W High Performance Active Heavy Subwoofer Speaker Arbitrary Connection of Active Speakers - China Speaker and Subwoofer price | Made-in-China.com