I'll try to get something together with a diagram, the relay has a major size advantage. I'm used to caling it a relay as that is what we typically referred to it as while I was installing, but it is really a 200 amp solenoid like you'd find in an electric golf cart, electric fork lift, or man lift. If you'd like to take a look at a picture check out mcmaster-carr at www.mcmaster.com and look at page 826