Monster THX SL200-PSM BK Select Certified Powered Subwoofer Tower Module (Piano Black) (Discontinued by Manufacturer) Dimensions: 14.2" L X 13.2" W X 29" H Weight: 53 lbs. THX Select certification delivers movie theater quality sound in the comfort of your own home. Curvilinear enclosure cancels standing waves for clear imaging and a deeper, more precise soundstage. 24k gold contact conductive plates let you drive a Monitor and a Bass Module with a single set of cables. 12" magnetically shielded woofer is driven by a powerful 200 Watt amplifier for clean, tight bass.