The biggest baddest sub woofer made.

The Parthenon. The ultimate loudspeaker driver.
More excursion, more output, higher power handling
than any driver on the face of the earth. A true
82mm one way linear stroke (nearly 6.5 inches
peak to peak linear), and a radiating surface
greater than three 18" subwoofers allows the Parthenon
to generate the highest SPL levels ever achieved
by a single driver (more output than eighteen
high end 18" drivers)...

[Link: adireaudio.com]