Product review (5 stars): A perfect replacement
Great product!  This was a perfect match for my Aprilaire 550.  I wish I had known it was coming with a strainer, though.  Then I wouldn't have bought a separate one.  Swapping out this one was easy.

One thing I was concerned about was that it was letting too much water through.  If you're wondering the same thing, there's a blog on the Aprilaire website that states:  "To check proper water flow through orifice, you would pull out the water feed tube, and have the water go into a 32 oz jar. That jar should fill in two and half minutes. If it fills way faster than that, you have too much water going in that it can not handle, and will leak out. The fix for that would be a new orifice."

It took just over 3 minutes to fill my container, so my flow was just fine.  It's good to know everything is working right.