Polk Audio M702 Features
Advanced driver material for even more realistic sound: 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
PowerPort technology for smooth, deep bass: Like all LSi M speakers, the 6-1/2" woofer in each of the 702 f/x speakers has its own PowerPort. Designed exclusively by Polk, this specially designed "cone" at the mouth of the bass port directs moving air to eliminate bass-stealing turbulence
Solid cabinet design for versatile placement: The 702 f/x cabinets are made of heavily braced 3/4" thick MDF with even thicker front baffles (1-1/4") to keep sound-coloring resonances to a minimum. The magnetic grilles easily snap on and off

Order now: Polk Audio LSiM 702 F/X Surround Speakers (Pair) $349 from adorama.com