CZC AUTO Battery Quick Disconnect Switch Top Post Cut/Shut Off Battery Master Isolator Switch for Boat Car Truck RV Camper Tractor Vehicles

There are a few different variations of it. I use this one. Some have a push button or knob you turn, but they all do the same thing, and that is to disconnect the circuit so electrons can't leave the battery. So if you turn the key, nothing will happen, and if you pop the hood, it will look like everything is wired up properly. It saves my battery and makes my car a lot harder to steal quietly and quickly.