The low and mid-range is reproduced by a 5.25" FCDTM cone driver. FCD stands for Fabric, Ceramic, Doping. It is made by first creating the cone's shape using a strong, and extremely lightweight fabric. A ceramic coating is then hand applied, heated, and hardened to give the cone its stiffness. Finally, a slightly sticky polymer coating (doping) is also hand applied that helps increase bass response and add warmth to the overall tone. FCD offers the smoothest and most natural sound of any cone material we have ever tested.