At last a superior fix for water supply to your boats inner transom assembly that feeds your engine its water supply. Corrosion in know to cause massive restrictions, restricting the supply of water to your engine sea water pump.
*SYMPTOMS* you may need this unit is that your engine is over heating with no apparent cause in that the sea water pump impeller is in good working condition and you cannot overcome unusual high water temps. When water is starved to your sea water pump it cause premature wear and blade tip breakage AKA pump failure.