Eminence 15" subwoofer with 3" coil, cast frame and Rubber surround. Bumped and vented magnet allows extra excursion without bottoming. These were custom built for a premium pro audio brand for a compact powered subwoofer with low tuning and some DSP optimizaton. You can squeeze this into 2-3ft and tune it around 40Hz with steep subsonic below for lots of clean bottom end in not a lot of space. Makes a perfect replacement for many powered 15" subwoofers. This is not built for midrange so it should be used as a subwoofer or a woofer in a 3way configuration. See test specs in the images. This is similar in build to an Eminence kappa pro 15lf-2 - don't be swayed by what seems to be low power handling, OEM specs always show a very conservative power rating. This would probably be rated at 1000 watts peak by regular "retail" standards...