HIFONICS APOLLO HPX600.4 APOLLO SERIES 600W 4 CHANNEL SPEAKERS AMP CAR AUDIO STEREO 4/3/2 CHANNEL OPERATION AMPLIFIER A/B Analog Class Amplification that is Blue "Military Grade" PCB High Dissipation Heat Sink that is 4/2 Ohm Stable High Speed MOSFET Output Devices Multi Channel 5/4/3/2 Channel Configurable with Variable Low Pass High Pass and Band Pass PWM Power Supply RCA Inputs/Outputs and Built-in system Diagnostics