The 701-1/20 cartridge filter is a nominally rated “701 Premium” filter, manufactured by Harmsco Filtration. The filter is 2.5″ in diameter and has a particle retention rating of 1 micron. The filter is 20″ in length and has NSF 61 Certified Polyester Cellulose filter media. This filter is a double open end, (DOE) configuration. All filters are individually wrapped.