CONTROL YOUR SAPPHIRE SCREEN WITH THIS CLEVER BLACK BOX THAT PLUGS INTO THE POWER LINE ON THE PROJECTOR Connect the Power Synchro Relay to the power cord of the projector and the RF-IR converter to the screen to create a synchronized control system. The Power Synchro Relay is designed for projectors that do not have trigger outputs. It detects the power current of the projector and transmits a wireless signal to the receiver. When the projector is turned on, the projection screen will automatically lower. When the projector is turned off, the projection screen will automatically retract.