I loved the simplicity and effectiveness of this inexpensive do-it-yourself alarm from GE. The GE Ceiling Mounted Motion Sensing Alarm is battery powered and just attaches to the ceiling of a hallway, entrance way or any room you wish to protect. Arm it with the included keychain remote, and if someone enters the area it sets off a loud alarm. The alarm looks like a smoke detector although it is not a functional smoke alarm. Simple, effective and installs in minutes. Perfect for homes, businesses, dorm rooms, cottages, bunkies, etc.