At one time anyone running an electric fuel pump had to have a shut off triggered by the car or engine in our racing organization. They settled on a rear bump switch like modern cars a few years later but I installed one in the oil pressure system with a 15psi cut off to the ignition. It looks like this one you press the button that’s at 7:00 o’clock while starting and let go when you see oil pressure. Just a guess it’s internally wired. They had to make it easy and pretty fool proof.