BRK, 120V ACDC Photo Smoke Alarm, Includes A Large Opening In The Mounting Bracket For Easy Access To Wiring, Key Hole Slots In The Mounting Bracket Eliminate The Need To Remove The Electrical Box Screws For Installation, Battery Pull Tab Keeps The Battery Fresh Until The Home Is Occupied, Battery Installation Removal Can Occur While The Unit Is Mounted To The Ceiling Or Wall Via The Side Load Battery Compartment, 2 Locking Features Are Provided To Prevent Battery Theft Or Theft Of The Unit, Connection To Ac Power Is Made With A Quick Connect Wiring Harness, Easy Installation Maintenance