Product review (1 stars): NOT an AutoFlo OEM part
I bought this valve based in part on the previous review that said this was an AutoFlo valve, and the fact that it had an AutoFlo part number, #25019.  The valve I got is not an AutoFlo OEM valve but a Chinese made universal valve not specific to the AutoFlo 250. The original AutoFlo valve on my humidifier was made by Parker in the USA.  It has a specific orifice size (1/16") designed to work with the AutoFlo 250 without dumping water out of the housing or down the drain.  This valve has no marking as to the size of the orifice and flows too much water for the humidifier.

Contact your local Parker Fluid Control Division rep and get the correct valve, part #3121BBN1GN00RBT1J1P0, or you can get a 1/8" needle valve to install down stream from this valve to adjust the water flow.  The correct valve will probably cost you more but it will work properly without any extra fiddling.