Actually, this link might be more what you want.
http://www.cutlersupply.com/store/item.0761.html I have a slightly simpler version. I use them for brooder thermostats. They have shorter knob shafts (genetics), so they have to be mounted in a spot without much insulation. I was disappointed in this, as I wanted to use a couple for a hatcher, using a cabinet with 1 inch walls. I'll measure one in the morning, for you.
I also have a few with remote bulb sensors that mount outside, with probe mounted wherever you want it. They wouldn't be a lot cheaper than the one at Cutler's, but sensor could be mounted nearly anywhere.
What size/type incubator do you have?