BP2004TL Floor Standing Bi-Polar Tower Speaker with Active Subwoofer Built-in Bi-Polar design provides open soundstage for front mains or rear surrounds Powered woofer built-in. Saves floor space by making seperate sub unnecessary. Clean black design does not detract from acoustics and price point. You're not paying for fancy veneers that do not contribute to sound quality Flexible connections allow for multiple surround sound set-up configurations Discrete level control on speaker allows you to "dial in" sub output discretely left and right. Maybe your room isn't symmetrical and the left side needs more "kick" because of any open door way nearby on the left, for example.