This Niles current-sensing 12-volt trigger lets you automatically turn on a secondary device when you power up the first. For example, activate a motorized projection screen when you turn on your front projector. Plug the Niles trigger into an AC outlet, and connect your projector to the trigger's AC input. Then run a mono minijack cable (not included) from the Niles trigger to your screen's 12-volt trigger input. Fire up your projector, and the screen extends you're ready for movie night.