This is the view through the door. The door is made from a double paned window. There is a shelf in front the heating element that holds a pan of water. There is a big fan that sucks from the bottom of the shelf and blows through the heating element. The air that the fan is pulling from the bottom is brought up through a false wall in the back of the incubator. A hole at the bottom of the false wall helps the air circulate evenly. This bator has three removable racks ( these were removed for cleaning), that are all connected to a rod that sticks out the side to turn the trays all at once. Those three white circles by the wafer are where they sit. Each rack can hold 8 dozen large eggs. That's 288 eggs if it was full. So it can hold 24 dozen eggs total. I won't be hatching that many at once, but could set that many. The insulation is 1/2" Styrofoam covered with 3/8" plywood. This bator works very well and only cost about $100 to make! We get a great hatch rate. That cheap white thermometer isn't used anymore, my kids just put it in for the picture. You can see the water weasel in the bottom. The black cord on the right is from the probe in the weasel. The thermometer sits on top. The glass in etched with a Partridge Cochin rooster and "Sclanimals". It is VERY heavy and very large!