Homefires' reeded firebox panels come in two versions:

Vermiculite (black or beige) - each panel measures 24" Wide x 40" High

Cast Iron (black) - 1 panel 40" Wide x 40" High, 2 panels 20" Wide x 40" High

The vermiculite is a great alternative to cast iron since the material is lightweight and can be easily cut down to size with a traditional wood saw. Plus, the material can be easily painted with heat resistant paint on the reeded or smooth side of the panel. But, no matter how easy the vermiculite is to deliver and install, nothing will ever be the same as actual cast iron panels.