For built-in fuel tanks. Protects environment and complies w/fuel discharge regulations. Helps avoid refueling spills because surge-free line causes automatic fuel nozzles to shut off as the tank fills. With non-automatic nozzles, the surge protector causes a gurgling sound to indicate that the tank is full. Withstands oil, gas, alcohol-blended fuels. Glass-filled polypropylene construction and surge-ball design. Sonic weld seal cannot be disassembled in the field (to prevent damage to unit). Compact size allows installation inside gunwale, even on small runabouts. Simply installs in-line with traditional tank vent systems that use standard 5/8" ID vent hose. Operates in any orientation within 45 deg. of vertical. Complete with hose clamps (2) for installation in vent hose.