This was a lot easier than I thought it would be. There is a relay unit that comes with the DEI backup battery. You have a positive and negative constant, to feed the backup, with a fuse. You have a positive and negative plug going from the module to the backup battery. Last, you have a positive lead, and a (-)trigger wire leading back to your alarm. Really easy to put in, and I feel a lot more confident about my alarm system in general. The unit was small, and easy to hide. If someone disables or disconnects my battery, the unit keeps power to the alarm, and triggers an immediate response. It was fun to test. It's a large piece of mind for the $30 or so that I spent.