The 3.5 inch ultra-thin Woofer uses a Die-cast Aluminum frame and an oversized voice coil with short coil width is connected to the cone. This double radial and long magnet system provides high excursion and no stray magnetic field, while a large hole is punched in the bottom of the U-yoke to reduce air pressure at the high excursion. The black anodized cone and dust cap extend the frequency response to high frequency.