The Omnipure K-Series K2350 inline filter has 1/4 FPT and 3/8 FPT fittings on both sides. This filter has KDF-55 in it to help reduce specifically chlorine, and heavy metals. It can also be used in refrigerators, ice makers, any under the counter reverse osmosis or water filtration unit.
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.