Add extra wireless Door / Window Detectors to your ERA alarm system to protect other areas of your property. These Door / Window Detectors will set off the alarm when a person opens a door or window on which they have been installed. Use on front and back doors or any other entry point such as larger windows and additional doors. These Magnetic contact detectors can also be used on the inside or outbuildings such as garages and sheds with 25m of the control panel.