The Omnipure K-Series (K2320) filter is a post carbon filter for RO systems. This filter helps in removing all types of contaminants in your water including sediment, bad taste, water odor, and chlorine taste and odor. It is a 1 micron filter and comes in 1/4" FPT, 1/4" QC, and 3/8" QC fittings. Dimensions: 2" W X 6" L Rating: 1 Micron Rating Flow Rate: .5 GPM Maximum Pressure: 125 PSI Maximum Temperature: 100 F Service Life: 1 Year or 1000 Gallons Filtration Media: Carbon Block Reduces: Chlorine Taste Odor Reduces: Particulates Class 1 Fitting Size: 1/4" FPT, 1/4" QC, 3/8" QC National Pipe Thread (NPT) Size Measured Against a Ruler* Actual Diameter (Inches) National Pipe Thread (NPT) (Fractional) 0.405" 1/8" 0.540" 1/4" 0.675" 3/8" 0.840" 1/2" *NOTE: A very common misconception is that a 1/4" NPT measures as 1/4 inch on a ruler or tape measurer. However, that is not the case. NPT will measure larger in diameter. Above is a sizing reference to help clarify.