A 10 micron replacement cartridge for billet inline fuel filter housings. Ten microns is the fine end of the scale and is the rating normally specified after the pump, immediately upstream of the fuel rail, where the aim is to stop particles small enough to score an injector pintle or lodge in a regulator seat. Fit it as the second stage behind a coarser pre-pump filter rather than as the only filter in the system, otherwise it will load up quickly and start to restrict flow. Replace or clean it as part of routine servicing, and always note the housing’s flow direction on reassembly. Confirm the element dimensions suit your particular filter body before ordering.