ANV-515 Dual Coils Passived Sub-Woofer Speaker,Silver Good for either passive sub-woofer or easy to build-in your own amplification. Heavy duty with solid sound box and driver. Easily to shake your room. Aluminum & Magnesium Alloy Metal Corn 10 Thick MDF Sound Box, Stand 200lbs weight on top. 3mm Thick Aluminum Back Panel, easy to drill holes or cut square opening for your DIY project.