Klipsch RP-600M II Reference Premiere Bookshelf Speakers, Pair90 X 90 SILICON COMPOSITE HYBRID TRACTRIX HORN Horn loading maximizes efficiently and increases detail while focusing high frequencies towards the listening area. Proprietary Tractrix geometry provides the most efficient transfer of high frequency waves into the listening area. The phase plug and compressed molded silicon face ensure smooth frequency response. When combined, the cleanest, most natural sound possible is created. The second generation