Monoprice Monolith THX Certified 8in 150-watt Powered Subwoofer, Deep and Powerful Bass, Compact Design, Quick and Easy To Setup, For Home Theater or Gaming Systems - Walmart.com
Amazon.com: Monolith 13 Inches THX Ultra Certified 2000 Watt Powered Subwoofer Massive Output, Low Distortion, for Studio and Home Theater Systems : Electronics
M&K Sound unveils new line of THX Certified® reference subwoofers