The STA-10 Features an Ultra Efficient Class D mono amplifier perfectly matched to power the 10-inch woofer in our exclusive passive radiator design for more bass in less space. Powerbass developed a compact trapezoid shaped enclosure, perfectly tuned to get the most out of the proprietary 10-inch subwoofer. The geometric design maximizes transient response, reducing the negative effects that a small enclosure can have on the subwoofer by dispersing and dissipating standing waves away from the subwoofer and the result is cleaner, deeper bass in a very small space.