Yeah, and it would be too hard to get shelves in them. Another thing is the door opens outward and that will cause all your hot air to escape instantly.
I prefer to build my own box out of wood so I can make it the correct size for the trays I intend to use. People frequently do it backwards, first making incubators then finding their preferred hatching box wont fit.
I like sliding plexi doors for the front, as one can be opened at a time preventing the complete loss of heat.
Insulated boxes are not really required if you use plywood and have tight control with your electronics, which will make up for losses quickly, but slow response systems using fish heaters or mechanical bi-metal themostats will have greater stability with some insulation.
Here's a pic of some of my incubators stacked in a closet, which also helps stability
Linear Mode
