One of our major speaker breakthroughs was IMPP (Injection-Molded Polypropylene), which allowed cones to be lighter AND more rigid. Then we added long stands of Aramid fibers into the mix, for extra strength. Now, we’ve gone even further by adding a second type of Aramid fiber that makes the cone even stronger and tougher, without adding weight. So what does this mean to you? Tighter, more powerful bass. A rich, natural sound character with excellent midrange depth. And the durability to stand up to the high volume levels, humidity, and temperature extremes that thrash other speakers.