Kidde i4618AC Hardwire Smoke Alarm Easy Installation - Front battery pull tab allows battery activation without removing alarm from mounting bracket. Large mounting base makes mounting easier, protects surface paint from dirt and covers imperfections. Pre-stripped wiring harness with easy off cap does not require stripper tool. Tinned strands increase conductivity and wire nut grip. Fewer Callbacks - Large centrally located Test/Hush alarm control button. Dust cover protects sensor from contaminates during construction reducing nuisance alarms. User-Friendly Features - Easy access front loading battery door. Battery backup provides protection in case of power failure. Interconnectable with up to 24 devices (of which 18 can be initiating) including smoke, CO and heat alarms. See users guide for complete instructions. Alarm memory flashes red LED indicating which unit was the initiating alarm in interconnected system. Temperature Range: 40 degree Fahrenheit to 100 degree Fahrenheit Tamper resist locking feature deters alarm theft