PowerPort® technology Designed exclusively by Polk, this specially shaped "cone" at the mouth of the bass port directs moving air to eliminate bass-stealing turbulence. No turbulence means no wasted power, which means more efficient bass response. High-quality tweeter performance The ring radiator tweeter features several improvements from the version in the earlier LSi line. A slight reshaping of the tweeter's bullet-shaped phase plug allows it to move even farther out of the baffle, while a redesigned diaphragm has made the tweeter even more efficient. Advanced driver material The original LSi speakers featured a light, stiff mineral-filled polypropylene cone that was "puffed up" with injected air to form a honeycomb-like structure. The new super cell aerated polypropylene uses larger "puffed cells" to create a cone material that's thicker yet lighter than the original.