The S-Series speakers have a large voice coil. The 6.5-inch and 6x9-inch models have a 35-mm voice coil, and this large voice coil size increases their driving power and control of the motor. The S-Series speakers are the first in the industry to use a material called CFRP (Carbon Fiber Reinforced Plastic), a very lightweight yet rigid material. On a standard, off-the-shelf oval cone, the edges are naturally weaker than the center due to the elongated shape. *Installation Available