Polk Audio DXi460P 4x6 Plate-Mounted Speakers Dynamic Balance driver technology for pure, distortion free sound. 3/4" silk dome tweeter delivers clear, well-defined highs Klippel optimized components using a state-of-the-art Klippel distortion analyzer Durable butyl rubber surround won't fall apart under the stress of extreme temperatures, sunlight or time, for years of great Polk sound Dynamic Balance Polymer/Mica composite cones are stiff yet lightweight for big sound, small distortion.