Kevlar-impregnated paper woofer cone- This combination has been chosen for its high strenght-to-weight ratio, and is formed using a proprietary manufacturing process. Besides improving transient response, this cone material adds stiffness to relieve stress concentrations that may accumulate at the base of the cone under high-power and high-pressure applications. This is the same cone used in our flagship GTi series subwoofers.Proprietary die-cast frame - The frame on Power Series is borrowed from our flagship GTi subwoofers. The thick wall construction offers maximum rigidity to support the heavy motor structure, and its fully vented architecture provides maximum movement of air behind the cone and spider for maximum cooling. Maximum rear-window area is provided to minimize acoustic compression of the cone's motion at high excursion.Nitrile-butylene-rubber one-piece surround and gasket - This material provides an optimum blend of elasticity and internal damping, resistance to ultraviolet radiation, and durability despite extreme temperature and humidity variations. The large size of the roll was optimized to offer good long-throw linearity with the proper amount of control and stability at excursion limits.