Part of the look of a real wood fire is the ashes and embers that have fallen down to the bottom of the hearth when the fire has been burning a long time. The Peterson Real-Fyre system uses vermiculite as part of the set up in order to emulate that glowing ember bed. If you are a professional installer, you may want this case that provides twelve 24-oz. bags of vermiculite so that you will be ready for your next several projects.