IPX67 RATED Waterproof multi-layer circuit boards for marine applications - Balanced differential inputs for noise-free operation regardless of the source - Full-range digital Class D technology with Direct FET power MOSFET output stage - 12dB per octave adjustable crossovers and phase control for system tuning. Selectable 3 option Auto Turn-On Mode circuit designed to work with ANY OEM head-unit, simplifies installation.