Yeah, my old original and my 2 'knock off' GQF's have the wafers....once dialed in they run for years without tinkering with them. Wafer thermostats were all you had when I was a kid and hatching eggs.
Actually, as I stated, it over rides the digital thermostat on the first incubator and on the second incubator, it plugs into the second outlet on the plug but since it has no temperature probe for it, it will operate at the same parameters set up on the first incubator.
So I set the parameters the same for both incubators, just in case some weird quirk should happen while I'm incubating.
I really like the Inkbird series of temperature controllers. I use to have to make temperature adjustments all the time to my cheap foam incubators but after getting the Inkbirds, that problem went away, they hold the temperature where ever you dialed into it, doesn't lose it's setting just because of a power failure or shutting it down til next season, just plug & play. No need to make adjustments.