Hertz SPL Show subwoofers are the ideal solution for building mobile audio systems with emphasis placed on low frequency power and impact. Featuring a stacked triple magnet motor assembly and 2 + 2 ohm dual voice coil, the three models (SX250D, SX300D, SX380D) differ only in their cone diameter. They feature a dual spider design and a four-layer voice coil wound on an extraordinary long aluminum former. The Back Vented Spider Support decreases voice coil operating temperature, even during enhanced SPL usage. By connecting the two voice coils in parallel, impedance is cut in half, making the most of the amplifier’s available power and achieving even higher sound pressure levels.