Product review (5 stars): Perfect Fit OEM Evaporator Panels
I ordered the two-pack of panels, and was pleased to see they matched the original OEM panel in my Aprilaire 700 humidifier.  They fit perfectly, and were a perfect match down to the clay coating and colored marks to denote the top of the filter.  These were a great value to replace the the original panel and get my furnace ready for the upcoming heating season.

The panels came complete with installation instructions.  I've attached a photo showing what it looks like.