Custom made powered subwoofer featuring a TC Sounds LMS15 15" subwoofer and 540W Dayton Audio SPA500 plate amp built into the enclosure. The enclosure is sealed with an internal volume calculated from the thiele small parameters of the speaker. The enclosure is made from 3/4" MDF (glued and screwed) with mahogany stained and polyed birch ply on sides front and top. Ive been making speakers for many years (you will have to trust me on that- or just call me and we can chat). The subwoofer was originally $400, amp was $285 and materials were around $200. I know im losing my shirt on this so forget the labor, but its a great sub for home theater and I am sure you will be as pleased with the sound as I was. Dimensions are 18"W x 20"D x 22"H. Please don't hesitate to call me about details.