Like for instance if you use lights, it can simulate sunrises and sunsets.
Its a proportional thermostat, constantly adjusting temps so they stay within most times a tenth of a degree
But it can ALSO be switched over to run as an on/off thermostat.
Its SUPER simple to setup, I had mine going right out of the box with no problems
It also has the 4 probes like you saw, so for instance as long as a rack is all the same setup, one probe/output can control it just fine as long as you stay within the 400w I believe it is power output per probe.
I have 9 snakes and 17 eggs in an incubator and Im using 3 probes, the last one is setup telling me my room temps.
One of the best pieces of equipment you can buy