Amazon.com: Kenwood SW-15HT SW15HT Passive 100 Watts Subwoofer Home Theater Speaker Subwoofer Surround Sound Front Firing 8 Ohms : Electronics
Pioneer TS-A2000LB Passive Subwoofer, Powerful Enclosure Subwoofer with 700 W Maximum Power, 20 cm, IMPP Membrane, Black, Continuous Output Power 250 W : Amazon.de: Electronics & Photo
Amazon.com: KICKER TRTP 10-inch (25cm) Thin Down Firing Subwoofer and Passive Radiator Enclosure, 2-Ohm, RoHS Compliant : Electronics