A full 4 piece replacement set for a standard/conventional reverse osmosis system. Including the following:

 

 

Four set package includes:

 

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"

*NOTEA 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.