This is a 2013 First Alert Wireless smoke and fire alarm.
The round white plastic alarm has a photoelectric sensor that detects a smoldering fire, has an easy access battery door, a mute button, and is IRIS compatible. It uses 2 AA batteries which are included, and the instructions.
It measures approximately 4.5" in diameter and 2" deep.
This alarm is in great pre-owned condition, in original packaging, and untested.