Kidde Battery-Operated 4-Inch Smoke Detector & Carbon Monoxide Value Pack Batteries Included Experience the next level of fire safety with this Kidde smoke detector and carbon monoxide detector value pack. The Kidde Battery-Operated Photoelectric Smoke Detector Alarm 4-Inch Batteries Included model 10SDR is a compact 4-inch smoke detector that uses photoelectric sensor technology to detect visible fire particles associated with smoldering fires. New 9th Edition sensor technology reduces false alarms often caused by cooking or shower steam while internal components of the smoke alarm self-test to ensure that it s always operating as expected. (Self-testing is not a substitute for a manual push test of the alarm. Perform a button test once per week to verify proper alarm operation.) The Kidde Smoke Detectors compact 4-inch design which is smaller than the average 5-inch smoke detector provides smoke detection in small spaces such as a mobile home RV or crawlspace. When smoke or fire is detected