Polypropylene Prefilter, hydrophobic, 30 µm, 47 mm This is a 30.0 µm pore size polypropylene prefilter constructed of 100% virgin polypropylene media. This filter is ideally suited for general clarifying & prefiltration applications including solvents, deionized water & bioburden reduction.; Synonyms: Hydrophobic polypropylene membrane prefilter,Polypropylene membrane filter; find Millipore