Amazon.com: Car Vehicle Subwoofer Audio Speaker - 6 Inch Competition Grade Pressed Paper Cone, 4 Ohm Impedance, Advanced Air Flow, 400W Power for Stereo Sound System - Audiotek K706 (1 Subwoofer) PK1 : Electronics
Skar Audio EVL-65 D4 6.5" 400 Watt Max Power Dual 4 Ohm Car Subwoofer : Electronics
Amazon.com: Pyle 6.5 Inch Mid Bass Woofer Sound Speaker System - Pro Loud Range Audio 300 Watt Peak Power w/ 4 Ohm Impedance and 60-20KHz Frequency Response for Car Component Stereo PLG64 : Electronics
Amazon.com: Goldwood Sound, Inc. Stage Subwoofer, Dual Voice Coil 12" Woofers 260 Watt each 6ohm 4 Speaker Set (GW-412D-4) : Musical Instruments
Amazon.com: LANZAR 6.5 inch Car Subwoofer Speaker - Black Non-Pressed Paper Cone, Aluminum Voice Coil, 4 Ohm Impedance, 600 Watt Power and Foam Edge Suspension for Vehicle Audio Stereo Sound System -