10th Anniversary Edition - W7 13.5-inch Subwoofer (1500 W, Dual 1.5 ? voice coils) Words like "extreme," "reference" and "ultimate" get thrown around quite a bit in the Subwoofer world, but rare is the product that can honestly lay claim to them. The 13W7AE does. Taking the W7 design formula to its highest level, the 13W7AE offers a staggering linear excursion envelope that exceeds 1.25 inches (32 mm) one-way, along with a suspension capable of over 4-inches of peak-to-peak excursion. Combine that with a piston diameter that is 28% larger than the 12W7AE's, and you have a serious high-performance driver for the most demanding applications. With a 13W7AE, limits simply vanish and amazing sub-bass happens... on all fronts, at any level. Our most potent Subwoofer is best used with amplifier power in the 500W - 1500W range and is optimized to operate in a 1.875 cu. ft. (53.1 l) sealed enclosure, or a 2.375 cu. ft. (67.3 l) ported enclosure. W7AE (Anniversary Edition) Subwoofers celebrate the 10th Anniversary of the launch of the W7 subwoofers. Functionally, they are identical to the original W7's, but they are distinguished by the following cosmetic differences: Satin-Black Powdercoated Baskets Bright Anodized Surround Clamp Ring Anniversary Edition Cone Badge Anniversary Edition Terminal Label