Alpine PDX-4.150 4/3/2 Channel Power Density Digital Amplifier Frequency Response (Hz): 20 - 20kHz External dimensions (WxHxD) in: 10-1/8 x 7-9/16 x 2-7/16 Built in Crossover: Built-in Variable Low-pass/ High-pass Filter Bass Boost: Variable Bass Boost Input Voltage (volts): 10.5-14.4