It is a pre-built unit that can be used to do exactly the same thing the DIY units described here will do.
Take the plate off where the heater would sit.
There is a small tube sticking up in the center -- it is driven by the motor.
Super glue a piece of PVC to that tube (make the tube as long a you need to mount the unit out of the water and ensure the powerhead will be in the water).
Mount the Powerhead on the other end of the PVC.
Mount the unit => upside down so the PH is in the water and the base uint isn't.
Plug the PH into the outlet on the unit.
Plug the base unit into an outlet and turn it on.
It's just simpler than building one.
Or as mentioned, take it apart and you will have the motor, switch, outlet, etc already wired. Put it in a utility box as in this thread.
I paid $5 ea for 10 of these at the end of winter so they were much cheaper than other sources of the motors.