Product review (1 stars): Needs the difficult to find 5/16" fittings.
This solenoid uses a 5/16" fitting while the broken Aprilaire 4040 I was trying to swap out for uses a 1/4" fitting. I have spent more money on fittings to try to convert this over than it would have been just to get the direct 4040 replacement.  They are not equivalents and should not be marketed as such.