P170618 Hydraulic Filter Fits CaterpillarOne New Aftermarket Replacement Hydraulic Return Line Filter Fits Caterpillar (Fits CAT) Industrial and Construction Equipment This hydraulic return line filter replaces the Fits Donaldson P170618 element and is designed for use in the hydraulic return line circuit of Fits Caterpillar (Fits CAT) industrial and construction equipment. The filter features microglass media with an outside to inside flow direction and an integrated bypass valve to protect