Product review (5 stars): Don't hesitate
At first I was reluctant to order these as they appear to be knock-offs but they're the real deal and fit fine.  The vendor has gotten them to me quickly and been good to work with.  On one order, one of the panels was crushed and the vendor replaced it without a fuss.  If you have an Aprilaire humidifier that requires this model, don't hesitate to save yourself money here.