I would not assume that's an H-bridge. Nothing in your link says it's an H-bridge or that it is capable of bidirectional control and the crude potentiometer control would also not be suited for an H-bridge since the zero point between forward and reverse is poorly defined.

To control a brushed DC motor unidirectionally is very easy...you just throw a MOSFET in series with the motor and put as many in parallel as required for the current. With a 40A rating, I could easily see this being the case.

I would not assume that's an H-bridge. Nothing in your link says it's an H-bridge or that it is capable of bidirectional control and the crude potentiometer control would also not be suited for an H-bridge since the zero point between forward and reverse is poorly defined.

To control a brushed DC motor unidirectionally is very easy...you just throw a MOSFET in series with the motor and put as many in parallel as required for the current. With a 40A rating, I could easily see this being the case.

I would expect an H-bridge that supports 40A involves considerably more components than what I am seeing here, even though the underside of the PCB is hidden.