Pioneer Pro Audio XY-215S Quasi-Bandpass Subwoofer - Dual 15" (Black)Dual 15 quasi bandpass subwoofer Key Features A quasi bandpass subwoofer with two 15 inch LF drivers. High response deep bass as low as 42 Hz is delivered to reproduce a tight and punchy kick. Two drivers efficiently generate air vibration to boost radiation efficiency. Requires an active crossover to set the necessary frequency range (presets can be provided from Pioneer for combinations using the Pioneer XY 152, XY 122, XY 101 and XY 81). NL4 INPUT