The listing, Kidde i9040 Fire Sentry Battery-Operated Ionization Sensor Compact Smoke Alarm has ended.
Battery operated 9V battery included
Test button tests unit's electronic circuitry horn and battery function
Four inch diameter discreet design
Easy installation
Meets the UL requirements and widely-accepted safety standards
Was purchased new and tried to install it before a family member installed another model for me. So this one has really never been used. Comes with battery, back plate, screws, etc. In great condition!