Focal Polyglass 100 CVX 4-Inch Coaxial Speaker Kit Built-in 12db/octave audiophile crossover Rotating and swivel mounted Aluminum inverted dome tweeter Polyglass cone made from a layer hollow glass micro-spheres over a cellulose pulp which greatly increases the rigidity of the cone without adding weight One inch voice coil for high power handling Rigid, non-resonant molded frame that is easy to install