A pre-filter is installed between the vehicle’s fuel tank and original fuel filter, and the simplest way to think about it is this filter catches rocks, and the factory filter catches remaining pebbles.
Glass fiber, Fuel filter paper, Composite paper
Cross Reference For P550547
CIMTEK EHS3030007 ; FLEETGUARD-FS1286
HASTINGS-FF910 ; VMC-FS550547 Donaldson P550547, P 55-0547