You looked at the website, right?
They are "controllers". They control pretty much everything.
Your lights, heaters, pumps, powerheads... anything you can plug in. Plus ph probes, temp probes, etc.
It will turn heaters on and off by temp, it can turn your lights off it the tank gets too hot, it can send alarms if anything is amiss, it can turn off any pumps/powerheads that you specify for a time period that you specify for feeding, and then turn back on automatically. TONS of stuff you can do to automate/simplify your tank.