Polk Audio - PAD4000.4 Digital Power Amplifier - 4 Channel - PAD4000.4. Super Efficient Class D Bridgeable 4-Channel Mobile Audio Amplifier.. Key Features:. Max power handling: 400W. MOSFET switching power. Efficient Class D bridgeable design. Channel Mode Switch (ST/4Ch). Toroidal transformers. Full, HPF, BPF switch. Adjustable low and high pass frequency. Front and rear level controls. Line level outputs and inputs. Nickel-plated wire terminals and RCA connectors. Stainless steel hardware. Protection: thermal, DC offset, reverse polarity and short circuit protection. Dimensions (with panels) - 1.81''H x 10.94''W x 6.75''D. WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.