The Flex Array TFA-600B Horn Loaded Subwoofer from Turbosound is a compact horn loaded bass enclosure designed to be ground stacked with Flex Array mid/highs in a wide range of concert touring applications. It consists of a neodymium 18" low frequency driver in a low distortion horn loaded design. This is the same drive unit as the one used in the flown single 18" TFA-600L and in the larger double 18" TSW-218 (both sold separately); the TFA-600B also employs the same loading techniques so that these bass enclosures can be freely mixed in any application.