MB Quart NA540.6 Nautic Amplifier, 6-Channel 540-Watt Gold-plated power, ground, speaker and RCA corrosion resistant connections Wide-range crossovers including high pass, low pass, and full pass Built-in diagnostics with visual indicators. Frequency Response: 10Hz-45kHz Conformal coated circuit boards resists corrosion from salt spray and moisture Non-corrosive aluminum heat sink