Product review (5 stars): Exactly the Parts that Degrade
This kit had everything I needed to make my humidifier as good as new.  The previous owners of my house did not maintain the humidifier.  Every part that came in this kit was used far beyond what was intended by Aprilaire.  After installing the parts in this kit, an incredibly easy endeavor, the humidifier works perfectly.  I'll be changing this every five years as suggested.